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  Subjects -> ENGINEERING (Total: 2235 journals)
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ENGINEERING (1194 journals)            First | 5 6 7 8 9 10 11 12 | Last

Journal of the University of Ruhuna     Open Access  
Journal of Thermal Science and Engineering Applications     Full-text available via subscription   (Followers: 3)
Journal of Thermal Stresses     Hybrid Journal   (Followers: 3)
Journal of Transplantation     Open Access   (Followers: 3)
Journal of Transport and Supply Chain Management     Open Access   (Followers: 9)
Journal of Transportation Engineering     Full-text available via subscription   (Followers: 13)
Journal of Transportation Systems Engineering and Information Technology     Full-text available via subscription   (Followers: 12)
Journal of Tribology     Full-text available via subscription   (Followers: 37)
Journal of Tropical Engineering     Open Access  
Journal of Turbomachinery     Full-text available via subscription   (Followers: 12)
Journal of Turbulence     Hybrid Journal   (Followers: 2)
Journal of Unmanned Vehicle Systems     Full-text available via subscription   (Followers: 2)
Journal of Urban and Environmental Engineering     Open Access   (Followers: 1)
Journal of Urban Planning and Development     Full-text available via subscription   (Followers: 31)
Journal of Urban Regeneration & Renewal     Full-text available via subscription   (Followers: 16)
Journal of Vibration and Acoustics     Full-text available via subscription   (Followers: 49)
Journal of Visualization     Hybrid Journal   (Followers: 2)
Journal of Volcanology and Seismology     Hybrid Journal   (Followers: 3)
Journal of Wuhan University of Technology-Mater. Sci. Ed.     Hybrid Journal  
Journal of Zhejiang University SCIENCE A     Hybrid Journal  
Journal on Chain and Network Science     Full-text available via subscription   (Followers: 3)
Jurnal Teknik ITS     Open Access  
Jurnal Teknologi     Open Access   (Followers: 2)
Karaelmas Science and Engineering Journal     Open Access  
Kerntechnik     Full-text available via subscription  
KKU Engineering Journal     Open Access  
Kleio     Full-text available via subscription   (Followers: 2)
Landscape and Ecological Engineering     Hybrid Journal   (Followers: 4)
Langmuir     Full-text available via subscription   (Followers: 48)
Latin American Journal of Computing     Open Access  
Leadership and Management in Engineering     Full-text available via subscription   (Followers: 10)
Learning Technologies, IEEE Transactions on     Hybrid Journal   (Followers: 9)
Lighting Research and Technology     Hybrid Journal  
Logic and Analysis     Hybrid Journal  
Logica Universalis     Hybrid Journal  
Lubrication Science     Hybrid Journal  
Machines     Open Access   (Followers: 2)
Machining Science and Technology: An International Journal     Hybrid Journal   (Followers: 3)
Macromolecular Reaction Engineering     Hybrid Journal  
Magazine of Concrete Research     Hybrid Journal   (Followers: 9)
Magnetics Letters, IEEE     Hybrid Journal   (Followers: 5)
Management and Production Engineering Review     Open Access  
Manufacturing Engineer     Hybrid Journal   (Followers: 4)
Manufacturing Research and Technology     Full-text available via subscription   (Followers: 3)
Marine Technology Society Journal     Full-text available via subscription  
MATEC Web of Conferences     Open Access  
Matériaux & Techniques     Full-text available via subscription   (Followers: 2)
Mathematical Models and Methods in Applied Sciences     Hybrid Journal   (Followers: 3)
Mathematical Problems in Engineering     Open Access   (Followers: 2)
Mathematics of Control, Signals, and Systems (MCSS)     Hybrid Journal   (Followers: 5)
Mauerwerk     Hybrid Journal  
Measurement     Hybrid Journal   (Followers: 3)
Measurement Science Review     Open Access   (Followers: 1)
Meccanica     Hybrid Journal   (Followers: 1)
Mechatronics     Hybrid Journal   (Followers: 4)
Medical and Biological Engineering and Computing     Hybrid Journal   (Followers: 3)
Medical Engineering & Physics     Hybrid Journal   (Followers: 10)
Membrane Science and Technology     Full-text available via subscription   (Followers: 3)
Membrane Technology     Full-text available via subscription   (Followers: 4)
Memetic Computing     Hybrid Journal  
Metabolic Engineering Communications     Open Access   (Followers: 2)
Metal Powder Report     Full-text available via subscription   (Followers: 20)
Metallurgist     Hybrid Journal   (Followers: 3)
Metaphysica     Hybrid Journal   (Followers: 1)
Metascience     Hybrid Journal   (Followers: 1)
Metrologia     Full-text available via subscription   (Followers: 1)
Microelectronic Engineering     Hybrid Journal   (Followers: 4)
Microelectronics International     Hybrid Journal  
Microelectronics Journal     Hybrid Journal   (Followers: 6)
Microelectronics Reliability     Hybrid Journal   (Followers: 8)
Microfluidics and Nanofluidics     Hybrid Journal   (Followers: 10)
Micromachines     Open Access   (Followers: 3)
Modelling and Simulation in Engineering     Open Access   (Followers: 3)
Modern Applied Science     Open Access   (Followers: 1)
Modern Information Technologies in the Sphere of Security and Defence     Open Access  
Molecular BioSystems     Full-text available via subscription   (Followers: 5)
Molecular Engineering     Hybrid Journal  
Molecular Pharmaceutics     Full-text available via subscription   (Followers: 15)
MRS Bulletin     Full-text available via subscription   (Followers: 5)
MRS Online Proceedings     Full-text available via subscription   (Followers: 1)
Multidimensional Systems and Signal Processing     Hybrid Journal  
NANO     Hybrid Journal   (Followers: 7)
Nano Letters     Full-text available via subscription   (Followers: 56)
Nano Research     Hybrid Journal   (Followers: 2)
Nano Reviews     Open Access   (Followers: 14)
Nano-Micro Letters     Open Access   (Followers: 1)
Nanopages     Full-text available via subscription   (Followers: 1)
Nanoscale and Microscale Thermophysical Engineering     Hybrid Journal   (Followers: 3)
Nanoscale Systems : Mathematical Modeling, Theory and Applications     Open Access  
Nanoscience and Nanoengineering     Open Access   (Followers: 1)
Nanoscience and Nanotechnology     Open Access   (Followers: 4)
Nanoscience and Nanotechnology Research     Open Access   (Followers: 3)
Nanotechnologies in Russia     Hybrid Journal   (Followers: 1)
Nanotechnology     Hybrid Journal   (Followers: 10)
Nanotechnology Magazine, IEEE     Full-text available via subscription   (Followers: 22)
Nanotechnology Reviews     Hybrid Journal   (Followers: 4)
Natural Hazards     Hybrid Journal   (Followers: 116)
Nature Nanotechnology     Full-text available via subscription   (Followers: 54)
Naval Engineers Journal     Hybrid Journal   (Followers: 2)
NDT & E International     Hybrid Journal   (Followers: 25)

  First | 5 6 7 8 9 10 11 12 | Last

Journal Cover Semiconductors and Semimetals
  [SJR: 0.549]   [H-I: 20]   [0 followers]  Follow
    
   Full-text available via subscription Subscription journal
   ISSN (Print) 0080-8784
   Published by Elsevier Homepage  [2801 journals]
  • Contents of Volumes in this Series
    • Abstract: Publication date: 2016
      Source:Semiconductors and Semimetals, Volume 94




      PubDate: 2016-01-10T23:34:57Z
       
  • Preface
    • Abstract: Publication date: 2016
      Source:Semiconductors and Semimetals, Volume 94




      PubDate: 2016-01-10T23:34:57Z
       
  • Contributors
    • Abstract: Publication date: 2016
      Source:Semiconductors and Semimetals, Volume 94




      PubDate: 2016-01-10T23:34:57Z
       
  • Copyright
    • Abstract: Publication date: 2016
      Source:Semiconductors and Semimetals, Volume 94




      PubDate: 2016-01-10T23:34:57Z
       
  • Series Page
    • Abstract: Publication date: 2016
      Source:Semiconductors and Semimetals, Volume 94




      PubDate: 2016-01-10T23:34:57Z
       
  • Nanowire-Based Visible Light Emitters, Present Status and Outlook
    • Abstract: Publication date: Available online 29 December 2015
      Source:Semiconductors and Semimetals
      Author(s): Bo Monemar, B. Jonas Ohlsson, Nathan F. Gardner, Lars Samuelson
      So far, the semiconductor nanowire research area has mainly delivered results on growth procedures and related material properties. As the development lately has been successful in producing novel nanowire-based structures for optical or electronic applications, the time is ripe to review the device work that has been done and in some cases has produced devices ready for the market. In this chapter, we shall review the specific area of nanowire-based LEDs (NW-LEDs) for visible light, including the application area of “solid state lighting” (SSL). A brief review of the progress in the area of visible light LEDs over the last half century is presented, this also mentions some of the progress made in the planar technology so far. The most successful way of producing white light is still based on the use of phosphors, just like in the present compact fluorescence lamps (CFLs). The reason for this is the high efficiency (external quantum efficiency>80%) possible at low currents in the violet planar InGaN-based LEDs used to excite the phosphors. These LEDs are presently mainly produced on foreign substrates, leading to a high dislocation density (DD) and a sizeable droop at high injection currents (25–40%). This droop and the down conversion energy loss in the phosphors (20–25%) has motivated the interest for a phosphor-less white light source based on direct mixing of light of different wavelength (such as red, green, and blue; RGB). To be competitive, this solution must be based on highly efficient LEDs for all RGB (red, green, and blue) colors. Since NW-LED structures can be produced basically free of structural defects (even if grown on a foreign substrate), the idea of using the RGB mixing concept for the production of white light sources with an ultimately higher efficiency than for the phosphor-based lamps is a major technical target for a second generation of light sources in the SSL field. Basic concepts behind the design and optical properties of NW-LED structures are discussed in this chapter, with emphasis on the present developments of III-nitride-based structures. The growth procedure relevant for such NW-LED structures is reported in some detail, specifically the core–shell configuration readily produced with metalorganic vapor phase epitaxy (MOVPE). The first generation processing technology for NW-LED structures is briefly described; this is naturally quite different from the established routines for planar LED chips. Experimental data for nitride-based NW-LEDs for blue, green, and even longer wavelengths are given in terms of radiative efficiencies, light outcoupling, droop, and long-term reliability. The experience so far is that for these NW-based emitters, efficiencies can be obtained that are close to those for the corresponding planar LEDs. There are still problems with the reproducibility of the radiative output, as well as a significant droop that would not be expected for m-plane emitters. More work is needed to pinpoint the cause of these problems. Finally, we briefly discuss various applications (also other than white lamps) where the NW-LEDs may have a specific advantage.


      PubDate: 2016-01-01T02:09:44Z
       
  • Semiconductor Nanowires for Energy Harvesting
    • Abstract: Publication date: Available online 29 November 2015
      Source:Semiconductors and Semimetals
      Author(s): Yanhao Yu, Xudong Wang
      Semiconductor nanowires (NWs) have been extensively studied for over two decades. Due to their one-dimensional morphology-related novel electronic, electrochemical, thermal, and mechanical properties, semiconductor NWs hold great promises in energy harvesting from light irradiation, temperature gradient, and mechanical deformation. This chapter provides a comprehensive overview of the most recent major advances of semiconductor NWs in the field of energy harvesting. NW-based photovoltaics are first reviewed with an emphasis of solar cells assembled from p–n junction, organic dye, polymer, quantum dots, and organometal perovskite. Developments of NW-based photoelectrochemical reactions are then discussed and compared from the groups of pristine, doped NWs, and NW heterostructures. NW-based thermoelectric and piezoelectric devices are reviewed and their unique advantages in thermal and mechanical energy harvesting are discussed. This chapter concludes with a brief perspective on future research directions and remaining challenges that would need to be overcome for utilizing semiconductor NWs in practical energy-harvesting devices.


      PubDate: 2015-12-04T06:15:43Z
       
  • Silicon Micro/Nanowire Solar Cells
    • Abstract: Publication date: Available online 29 November 2015
      Source:Semiconductors and Semimetals
      Author(s): Chito E. Kendrick, Joan M. Redwing
      Photovoltaic (PV) devices based on arrays of silicon wires with diameters in the nanometer to micron range have sparked considerable interest due to their attractive light trapping characteristics and the prospects to enhance carrier collection in radial junction structures. This chapter reviews fabrication techniques, design and testing considerations, and the PV performance of silicon wire devices. Common bottom-up and top-down wire fabrication methods are initially reviewed including vapor–liquid–solid growth, metal-assisted chemical etching, and deep reactive ion etching. Design considerations for wire array solar cells are discussed such as the impact of wire array geometry on light absorption and the effects of wire diameter and doping on PV performance. Device results for three common wire junction geometries are then reviewed including radial and axial junction wire structures and planar junctions with nanowire surface texturing. Methods to form radial junctions in silicon wires are compared such as the use of an electrolyte, thermal diffusion of dopants, and wire-coating techniques based on chemical vapor deposition. Applications for nanowire texturing of silicon monocrystalline and multicrystalline cells are described. The advances in device design and processing have resulted in continual improvements in the PV performance of silicon wire array devices to the point where efficiencies ranging from ~10% for radial junction cells up to as high as 22.1% for nanowire-textured devices have been reported.


      PubDate: 2015-11-29T06:15:53Z
       
  • Optical Properties of Semiconductor Nanowires: Insights into Band
           Structure and Carrier Dynamics
    • Abstract: Publication date: Available online 29 November 2015
      Source:Semiconductors and Semimetals
      Author(s): Howard E. Jackson, Leigh M. Smith
      This chapter describes how optical experiments on single semiconductor nanowires and nanowire heterostructures have illuminated both new physics and influenced the development of new growth methods that have resulted in nanowires of high quality. New physics here means the understanding of fundamental properties including band structures, the roles of symmetry and of strain in core/shell structures, the dynamics of excited electron–hole plasmas, and the exploration of more complex nanowire heterostructures like quantum well tubes. We will concentrate in this chapter mainly on the III–V materials such as wurtzite and zincblende InP, GaAs and GaAs/AlGaAs core/shell, and core/multishell heterostructures, where incredible improvements in materials quality have enabled the development of many new applications in recent years, from high efficiency solar cells, single nanowire lasers at room temperature, and single photon emitters, to a variety of chemical and biological sensors. We end the chapter with a brief mention of very recent experiments on some very new nanowire materials like InGaAs and GaAsSb whose bandgaps move distinctly into infrared wavelength regime.


      PubDate: 2015-11-29T06:15:53Z
       
  • Series Page
    • Abstract: Publication date: 2015
      Source:Semiconductors and Semimetals, Volume 93




      PubDate: 2015-11-29T06:15:53Z
       
  • Copyright
    • Abstract: Publication date: 2015
      Source:Semiconductors and Semimetals, Volume 93




      PubDate: 2015-11-29T06:15:53Z
       
  • Contributors
    • Abstract: Publication date: 2015
      Source:Semiconductors and Semimetals, Volume 93




      PubDate: 2015-11-29T06:15:53Z
       
  • Preface
    • Abstract: Publication date: 2015
      Source:Semiconductors and Semimetals, Volume 93
      Author(s): Anna Fontcuberta I. Morral, Shadi A. Dayeh, Chennupati Jagadish



      PubDate: 2015-11-29T06:15:53Z
       
  • Contents of Volumes in this Series
    • Abstract: Publication date: 2015
      Source:Semiconductors and Semimetals, Volume 93




      PubDate: 2015-11-29T06:15:53Z
       
  • Compound Semiconductor Nanowire Photodetectors
    • Abstract: Publication date: Available online 2 November 2015
      Source:Semiconductors and Semimetals
      Author(s): Xing Dai, Maria Tchernycheva, Cesare Soci
      Photodetectors based on quasi one-dimensional nanostructures—nanowires—formed of different materials have attracted large attention. The interest in these devices is motivated by the fascinating properties of nanowires, which offer new ways to improve the detector performance as well as to add different functionalities: the high surface-to-volume ratio of nanowires is key to the enhancement of sensitivity of nanowire photoconductors, while radial and axial junctions enable heterostructured nanowire photodetectors. Due to their small size, nanowires allow for ultimate detector miniaturization and facilitate their integration into compact photonic circuits. In this chapter, we review some general nanowire photodetector concepts and illustrate them by examples of recent experimental demonstrations using compound semiconductor materials.


      PubDate: 2015-11-02T22:38:11Z
       
  • Nanowire Tunneling Field-Effect Transistors
    • Abstract: Publication date: Available online 2 November 2015
      Source:Semiconductors and Semimetals
      Author(s): Joachim Knoch
      Field-effect transistors based on band-to-band tunneling (TFETs) have recently attracted a great deal of interest. The strong interest stems from the fact that TFETs potentially allow the realization of transistors with superior switching behavior compared to conventional metal-oxide semiconductor FETs and hence allow reducing the operational voltage as well as the off-state leakage current. As a result, integrated circuits based on TFETs potentially exhibit a substantially reduced dynamic and static power consumption and are therefore particularly well suited for low-power, mobile applications. However, although tremendous progress has been made recently, experimental realizations so far still lack a satisfying performance. While a number of apparent performance boosters have been identified in recent studies, their impact on the performance of TFETs becomes rather intricate and involved when spatial dimensions are reduced to the nanoscale such as in nanowire TFETs. The aim of this chapter is to study the various dependences isolated from each other in order to illuminate the interdependencies, impact, and effectiveness of different TFET performance boosters.


      PubDate: 2015-11-02T22:38:11Z
       
  • Theory of VLS Growth of Compound Semiconductors
    • Abstract: Publication date: Available online 26 October 2015
      Source:Semiconductors and Semimetals
      Author(s): Vladimir G. Dubrovskii
      In this work, we give a detailed overview of theoretical methods used for modeling the vapor–liquid–solid (VLS) growth of III–V semiconductor nanowires. We emphasis the importance of considering kinetics of both group III and V species for understanding and control over the properties of III–V nanowires in terms of their morphology and crystal structure. The chapter reviews the well-known results but also presents some newly developed concepts. In particular, we describe very recent results for nucleation rates in III–V nanowires under different conditions, the radius self-equilibration in Ga-catalyzed GaAs nanowires, and understanding the polytypism of Au-catalyzed III–V nanowires versus the group V flux.


      PubDate: 2015-10-28T05:15:43Z
       
  • Strain in Nanowires and Nanowire Heterostructures
    • Abstract: Publication date: Available online 21 October 2015
      Source:Semiconductors and Semimetals
      Author(s): Frank Glas
      This chapter examines strains and stresses in semiconductor nanowires, why they occur, how they manifest themselves, how they can be calculated and measured, and also how their possibly deleterious effects may be circumvented by an appropriate choice of geometry and materials. We focus on the specificities of nanowires in this respect and review theoretical approaches as well as experimental results. We first briefly recall the methods by which strains and stresses may be computed and the choice techniques used to measure them in nanostructures. In nanowires, strain manifests itself mainly when two crystalline materials with different lattice parameters are associated to form a heterostructure. We review successively axial heterostructures, nanowires on a misfitting substrate, and core–shell heterostructures. For axial and core–shell heterostructures, we examine in turn the calculations of coherent elastic relaxation and the main characters of the strain distribution, then the predictions about plastic relaxation, and confront these results to the rather scarce experiments that exist. Such interfaces between different materials have been studied for decades in planar semiconductor structures and in other types of nanostructures. In addition, nanowires present other instances where strain may occur. We examine some of these, in particular, the case of crystal phase heterostructures.


      PubDate: 2015-10-24T21:04:57Z
       
  • Quantum Dots in Nanowires
    • Abstract: Publication date: Available online 1 October 2015
      Source:Semiconductors and Semimetals
      Author(s): Luca Francaviglia, Yannik Fontana, Anna Fontcuberta i Morral
      Nanoscale filamentary crystals known as nanowires (NWs) are the ideal platform for the controlled fabrication of quantum dots (QDs). Thanks to the exquisite control in NW growth mechanisms, nanoscale insertions of foreign materials in NWs forming nanowire-based QDs, NWQDs, are nowadays possible. NW shape and axial dimensions also allow addressing them optically and electronically. Photonic design of the NW shape also guarantees maximized extraction of the QD emission. Overall, this is a vibrating area of research which should soon translate its knowledge into technology.


      PubDate: 2015-10-01T11:42:03Z
       
  • Hybrid III–V/Silicon Nanowires
    • Abstract: Publication date: Available online 26 September 2015
      Source:Semiconductors and Semimetals
      Author(s): Moïra Hocevar, Sonia Conesa-Boj, Erik Bakkers
      Semiconducting nanowires are emerging as a route to combine heavily mismatched materials. The nanowire dimensions facilitate the defect-free integration of the two most powerful semiconductor classes, group IVs and group III–Vs. These combinations may enhance the performance of existing device concepts and also create new applications. In this chapter, we review the recent progress in heteroepitaxial growth of III–V and IV materials. We highlight the advantage of using the small nanowire dimensions to facilitate accommodation of the lattice strain at the surface of the structures. Another advantage of the nanowire system is that the antiphase boundaries are not formed, as there is only one nucleation site per wire. In this chapter, we will discuss three different heteroepitaxial III–V/Si morphologies, III–V nanowires on group IV substrates, and axial and radial heterojunctions. Advanced analysis techniques are used to characterize the quality of the heterointerfaces. Finally, we address potential applications of III–V/Si nanowires.


      PubDate: 2015-10-01T11:42:03Z
       
  • Semiconductor Nanowire Optoelectronic Devices
    • Abstract: Publication date: Available online 1 October 2015
      Source:Semiconductors and Semimetals
      Author(s): Sudha Mokkapati, Dhruv Saxena, Hark Hoe Tan, Chennupati Jagadish
      Semiconductor nanowires act as waveguides despite very small cross-section dimensions because of high refractive indices. The waveguiding properties of nanowires alter the way the semiconductor material interacts with light. We elaborate on the waveguiding properties of nanowires and the effect of these properties on the spontaneous emission characteristics of nanowires. The effect of waveguiding properties of nanowires on optoelectronic devices like nanowire solar cells and lasers is also discussed.


      PubDate: 2015-10-01T11:42:03Z
       
  • Mechanical Behaviors of Semiconductor Nanowires
    • Abstract: Publication date: Available online 26 September 2015
      Source:Semiconductors and Semimetals
      Author(s): Yujie Chen, Xiaozhou Liao
      Semiconductor nanowires (NWs) have demonstrated many interesting physical properties that are not seen in bulk semiconductors due to the unique quantum mechanics effect in one-dimensional structures. The mechanical properties of semiconductor NWs, which are expected to be significantly different from those of their bulk materials because of the small NW dimensions, are a crucial factor in designing and manufacturing NW-based devices with predictable and reproducible operation. Because of their small dimensions, mechanical property testing of NWs is not an easy task and errors can be easily introduced in the measured mechanical data. Here, we review the techniques that have been developed to quantify the mechanical properties and to understand the deformation mechanisms of NWs, including bending, resonance, uniaxial loading, and nanoindentation. We also provide a general review of the mechanical properties and deformation behaviors of semiconductor NWs and discuss possible sources responsible for the discrepancy of measured mechanical properties.


      PubDate: 2015-10-01T11:42:03Z
       
  • Position-Controlled Selective Growth of ZnO Nanostructures and Their
           Heterostructures
    • Abstract: Publication date: Available online 5 September 2015
      Source:Semiconductors and Semimetals
      Author(s): Hosang Yoon, Gyu-Chul Yi
      In this chapter, we present a review of recent research activities related to position-controlled selective growth of ZnO one-dimensional nanostructures and their heterostructures for various device applications. The main text of this chapter is organized into three sections. The first section briefly introduces selective growth methods of ZnO nanostructures and describes the underlying growth mechanisms. It is of interest to characterize in detail the nanostructures grown by catalyst-assisted and catalyst-free methods, in an attempt to better understand the key factors required to create nanostructures with high crystallinity and low defect density for high-quality electronic and optoelectronic devices. In the second section, the position-controlled selective growth of ZnO nanostructures on various substrates and their resulting growth characteristics is reviewed. The diverse choice of substrates applicable to position-controlled selective growth of nanostructures includes various semiconducting substrates (e.g., Si, GaN, ZnO, SiC, and indium tin oxides), metallic substrates (e.g., Au, Pt, Cu, and Ag), and insulating substrates (e.g., Al2O3), covering the vast majority of substrates used in the device industry. In particular, layered two-dimensional materials, such as graphene and hexagonal boron nitride, have recently been emerging as novel substrates for transferable and flexible optoelectronic and electronic devices. The last section focuses on the fabrication of light-emitting diodes based on ZnO nanostructures and their heterostructures with GaN and its alloys. We first introduce the initial works that used vertically aligned but randomly formed ZnO nanostructures, and then move onto more advanced nanoarchitectures enabled by position-controlled selective growth. The position-controlled selective growth is essential in creating nanostructure devices suitable for practical applications, where the nanostructures are located at precisely determined positions with designed dimensions. Selective growth is needed not only to control the position of the grown nanomaterials but also to improve the performance of devices. Finally, conclusions and perspectives on ZnO nanostructures for various device applications are presented.


      PubDate: 2015-09-06T12:06:32Z
       
  • van der Waals Heteroepitaxy of Semiconductor Nanowires
    • Abstract: Publication date: Available online 3 September 2015
      Source:Semiconductors and Semimetals
      Author(s): Young Joon Hong, Chul-Ho Lee
      van der Waals (vdW) heteroepitaxy of semiconductors enables the integration of the semiconductor electronic and optoelectronic devices on virtually arbitrary substrates. In this chapter, we provide a review on recent progresses in the vdW epitaxy of semiconductor nanowires on two-dimensional atomic-layered materials (2d-ALMs). The efforts and challenges in various approaches for vdW epitaxy of semiconductor nanowires are reviewed. We pay particular attention in complementary studies on microscopically observed and theoretically simulated vdW epitaxial heterointerfaces. The methods of controlling the nucleation–growth processes for site-selective vdW epitaxy are discussed, followed by a brief review on optoelectronic device applications. The new opportunities and strategies for the vdW heteroepitaxial integration of semiconductors on 2d-ALMs are further discussed toward emerging functional electronics and optoelectronics.


      PubDate: 2015-09-06T12:06:32Z
       
  • Atom Probe Tomography of Nanowires
    • Abstract: Publication date: Available online 5 September 2015
      Source:Semiconductors and Semimetals
      Author(s): Nari Jeon, Lincoln J. Lauhon
      Atom probe tomography (APT) is a destructive material characterization technique that can analyze the composition of small volumes (~100×100×100nm3) of a sample with subnanometer resolution and part per million sensitivity. APT is therefore well suited to investigate semiconductor nanostructures in order to relate growth conditions to nanoscale structure and nanostructure to physical properties. Furthermore, the geometry of semiconductor nanowires facilitates their analysis by APT. This chapter is intended for scientists and engineers who are interested in using APT to characterize semiconductor nanowires or for those who wish to assess research findings derived from APT more critically and with a greater understanding of the method. We first introduce the principles of APT to provide the basic background needed to understand the capabilities and limitations of the method, and then briefly review experimental considerations including sample preparation, operation conditions, and reconstruction guidelines. We then present examples of the atom probe analysis of semiconductor nanowires focused on important analytical challenges including dopants and impurities, alloy fluctuations and clusters, and heterointerfaces. Concurrently, we explain key challenges to sample preparation and analysis and suggest approaches to overcome or circumvent these challenges.


      PubDate: 2015-09-06T12:06:32Z
       
  • Series Page
    • Abstract: Publication date: 2015
      Source:Semiconductors and Semimetals, Volume 92




      PubDate: 2015-06-29T03:35:41Z
       
  • Preface
    • Abstract: Publication date: 2015
      Source:Semiconductors and Semimetals, Volume 92
      Author(s): Gerhard P. Willeke , Eicke R. Weber



      PubDate: 2015-06-29T03:35:41Z
       
  • Contents of Volumes in this Series
    • Abstract: Publication date: 2015
      Source:Semiconductors and Semimetals, Volume 92




      PubDate: 2015-06-29T03:35:41Z
       
  • Contributors
    • Abstract: Publication date: 2015
      Source:Semiconductors and Semimetals, Volume 92




      PubDate: 2015-06-29T03:35:41Z
       
  • Copyright
    • Abstract: Publication date: 2015
      Source:Semiconductors and Semimetals, Volume 92




      PubDate: 2015-06-29T03:35:41Z
       
  • Silicon Crystallization Technologies
    • Abstract: Publication date: Available online 10 June 2015
      Source:Semiconductors and Semimetals
      Author(s): Peter Dold
      More than 90% of all Photovoltaic (PV) installations are based on crystalline silicon, several hundred thousand tons of which are processed by the solar industry each year. During the last few years, we have seen a huge price reduction in the polysilicon market. But still, the raw material contributes significantly to the total costs and further price reductions might be expected. Today, most polysilicon is produced by the Siemens process, but alternative routes like fluidized-bed reactors or upgraded metallurgical silicon might provide a better cost structure and thus might gain market shares. The majority of solar silicon is crystallized by the directional solidification method (also called vertical gradient freeze method). This technique is quite robust, easy to handle, and easily scalable. Block sizes between 500kg and 1ton are the actual standard. The latest development is the small-grain, high-performance multi. Compared to quasi-mono (mono-like) silicon, the better cost structure and the lower process complexity of the high-performance multi are a clear advantage. Some 40% of the silicon is crystallized as mono ingots. Right now, Czochralski (Cz) is the standard technology: 8″ or 9″ ingots of cylindrical shape and a length of 1.5–2m are grown. Since Cz is hardly scalable to larger ingots, the challenge is to reduce cost by accelerating the process, by reducing downtime, and by making a better use of the consumables. Actual trends are multipulling, feeding, continuous pulling, or active crystal cooling to mention just some of them. In particular, for high-efficiency cell technologies like Interdigitated Back Contact (IBC) or Heterojunction with Intrinsic Thin layer (HIT), high-quality n-type material is required. Finally, the Float-Zone (FZ) technique will be discussed. FZ ingots have at least two orders of magnitude lower oxygen levels compared to Cz material and the corresponding minority carrier lifetimes are very high. Right now, the process suffers by its complexity and the lack of affordable feed rods. Overcoming these limitations, FZ might be an interesting alternative for high-efficiency applications.


      PubDate: 2015-06-14T12:28:55Z
       
  • Reliability Issues of CIGS-Based Thin Film Solar Cells
    • Abstract: Publication date: Available online 10 June 2015
      Source:Semiconductors and Semimetals
      Author(s): Thomas Walter
      Solar cells based on Cu(In,Ga)Se2 (CIGS) have reached a high degree of maturity as confirmed by conversion efficiencies exceeding 21% on a laboratory scale and module efficiencies approaching 16%. However, maturity of a PV technology also requires reliability and long-term stability. Therefore, upcoming reliability aspects of CIGS-based solar cells are the focus of this chapter. Metastabilities, partial shading, PID, and the impact of the back contact will be presented and discussed regarding their influence on the long-term stability and reliability. It will be pointed out that an understanding of the underlying physics is essential not only to optimize the long-term stability but also to predict the lifetime of solar cells and modules. Especially, high-efficiency devices and the pressure to cut down costs impose an even higher challenge on manufacturers and researchers in the field of reliability. As an outcome, it will be shown that CIGS exhibits distinct beneficial properties with respect to reliability. However, the development of highly efficient modules also involves new reliability issues which have to be investigated in detail in order to assure the stability of this emerging PV technology.


      PubDate: 2015-06-14T12:28:55Z
       
  • Preface
    • Abstract: Publication date: 2015
      Source:Semiconductors and Semimetals, Volume 91
      Author(s): Lucia Romano , Vittorio Privitera , Chennupati Jagadish



      PubDate: 2015-06-10T07:00:51Z
       
  • Contributors
    • Abstract: Publication date: 2015
      Source:Semiconductors and Semimetals, Volume 91




      PubDate: 2015-06-10T07:00:51Z
       
  • Copyright
    • Abstract: Publication date: 2015
      Source:Semiconductors and Semimetals, Volume 91




      PubDate: 2015-06-10T07:00:51Z
       
  • Series Page
    • Abstract: Publication date: 2015
      Source:Semiconductors and Semimetals, Volume 91




      PubDate: 2015-06-10T07:00:51Z
       
  • Point Defects in ZnO
    • Abstract: Publication date: Available online 9 May 2015
      Source:Semiconductors and Semimetals
      Author(s): Matthew D. McCluskey
      Zinc oxide (ZnO) has promising properties for a range of optoelectronic applications, including efficient light emission and spintronics. Fundamental knowledge about dopants and defects in ZnO has expanded considerably over the past 15 years. In this chapter, the properties of point defects in this material are reviewed. An emphasis is placed on insights obtained through experimental techniques such as electron paramagnetic resonance, infrared spectroscopy, photoluminescence (PL), and positron annihilation. Substitutional donors and hydrogen donors are shallow, with binding energies ~50meV, and contribute to the prevailing n-type conductivity of ZnO samples. Acceptor dopants, in contrast, are deep. Substitutional nitrogen, for example, has an acceptor binding energy of 1.4–1.5eV. The oxygen (zinc) vacancy is a deep double donor (acceptor), but the energy level values are not known accurately. While there are intriguing hints of shallow acceptors from PL spectra, p-type doping remains an elusive goal.


      PubDate: 2015-05-10T19:54:41Z
       
  • Wafering of Silicon
    • Abstract: Publication date: Available online 18 April 2015
      Source:Semiconductors and Semimetals
      Author(s): Hans Joachim Möller
      Semiconductor bulk crystals have to be cut into wafers for further applications. The dominant slicing technique both for microelectronic and photovoltaic applications is the multiwire sawing method. The requirements on the processes and wafer qualities depend on the material and the application. The most advanced techniques have been developed for silicon. Sawing and the subsequent processes such as grinding, lapping, and polishing use abrasive particles for material removal. The fine-tuning and optimization of the wafer processes requires an understanding of the micromechanical interactions between abrasive particles and crystal. The current status of research and development will be described for the major methods and materials. Finally, a brief overview will be given for alternative wafer-processing techniques.


      PubDate: 2015-04-21T03:32:43Z
       
  • Electron and Proton Irradiation of Silicon
    • Abstract: Publication date: Available online 8 April 2015
      Source:Semiconductors and Semimetals
      Author(s): Arne Nylandsted Larsen , Abdelmadjid Mesli
      This chapter presents a review of defects in silicon produced by irradiation with electrons and protons of MeV energies. The review is confined to simple defects with less than three constituents as they are by far the most common defects found in silicon after such irradiations. The emphasis has been put on newer investigations, and in particular on unresolved issues like the lack of experimental observation of the self-interstitial, the diffusivity of the monovacancy, and the discussion as to whether the di-interstitial has been observed in electron paramagnetic resonance and deep level transient spectroscopy spectra. The branching reactions of the constituents of the Frenkel pair, the vacancy and the self-interstitial, are treated in some detail. It is demonstrated that to describe complex phenomena such as charge-controlled metastability, atomic relaxations leading to the so-called negative-U property of a defect, and many other aspects discussed in this review, at least a qualitative understanding of the various key ingredients involved in defect formation is indeed prerequisite.


      PubDate: 2015-04-09T19:25:38Z
       
  • Point Defects in Silicon Carbide
    • Abstract: Publication date: Available online 20 March 2015
      Source:Semiconductors and Semimetals
      Author(s): Naoya Iwamoto , Bengt G. Svensson
      In this chapter, we critically review recent progress in the understanding and control of intrinsic point defects, and hydrogen and transition metal impurities in monocrystalline silicon carbide. In particular, the 4H polytype is addressed which currently attracts large technological interest. The carbon vacancy (VC) is shown to be the most abundant electrically active defect in high-purity n-type 4H epitaxial layers, and it exhibits a formation energy of ~5.0eV with a rather high entropy factor (~(5–6)k). Further, VC is a charge carrier lifetime controlling defect and displays negative-U character in its negative charge states. The prominent and so-called Z 1/2 and EH7 deep levels in 4H–SiC are now unambiguously identified as different charge state transitions of VC. In contrast to VC, the silicon vacancy (VSi) exhibits a low abundance. VSi has a high electron spin ground state and is currently explored as a defect with long spin coherence time enabling long-lived qubits at room temperature. Experimental spectroscopic data for interstitials and antisite defects in SiC are scarce in the literature and our understanding relies mainly on results from ab initio modeling. Hydrogen is a prevalent residual impurity in p-type SiC and interacts strongly with acceptor dopants like Al and B leading to passivation of their electrical activity. Transition metal impurities in SiC receive an emerging interest and they are found to diffuse at high temperatures (≥1500°C) and also to form stable complexes with intrinsic defects. Finally, some suggestions for future research tasks are given.


      PubDate: 2015-04-05T05:20:50Z
       
  • Ion Implantation Defects and Shallow Junctions in Si and Ge
    • Abstract: Publication date: Available online 5 March 2015
      Source:Semiconductors and Semimetals
      Author(s): Enrico Napolitani , Giuliana Impellizzeri
      Defects produced by ion implantation in Si and Ge, their evolution upon post-implantation annealing, and their role in shallow junction formation processes in Si and Ge are reviewed in this chapter. After summarizing the main mechanisms underlying the defect generation and accumulation during the ion implantation processes, the damage evolution during post-implantation annealing will be treated, with emphasis on agglomerates of intrinsic defects in Si. Afterward, anomalous dopant diffusion and electrical activation phenomena occurring in Si and Ge after post-implantation annealing will be treated, with a particular focus on point defect engineering strategies for shallow junction optimization.


      PubDate: 2015-03-06T06:18:49Z
       
  • Role of Defects in the Dopant Diffusion in Si
    • Abstract: Publication date: Available online 21 February 2015
      Source:Semiconductors and Semimetals
      Author(s): Peter Pichler
      Silicon technology is based on doping with atoms from the groups III and V of the periodic system, which provide free holes or electrons, respectively. During processes at elevated temperature, these dopants may diffuse in the crystal. The basic mechanisms suggested for the diffusion of dopants in literature are reviewed. The most successful ones assume that dopants form mobile pairs with vacancies and self-interstitials. This assumption leads within the methodology of diffusion–reaction equations directly to a system of coupled continuity equations, which is shown to explain a variety of diffusion phenomena. Some of these diffusion phenomena are intrinsic to dopant diffusion particularly at high concentrations. Others are related to nonequilibrium phenomena associated typically to chemical reactions at the surface or in the bulk. At high concentrations, a variety of mechanisms may lead to the deactivation of the dopants. Besides precipitates and small complexes, particularly, the segregation at interfaces is discussed.


      PubDate: 2015-02-25T01:28:55Z
       
  • Point Defects in GaN
    • Abstract: Publication date: Available online 21 February 2015
      Source:Semiconductors and Semimetals
      Author(s): Michael A. Reshchikov
      In this chapter, a critical analysis of point defects in GaN and their manifestation in such experiments as photoluminescence (PL), deep-level transient spectroscopy (DLTS), positron annihilation spectroscopy (PAS) is presented. Only a few PL bands are attributed to specific defects. The dominant defect-related PL band in GaN grown by metalorganic chemical vapor deposition (MOCVD) or molecular beam epitaxy is the yellow luminescence (YL) band with a maximum at 2.2eV, which is attributed to the CNON complex. In DLTS studies, it is known as a hole trap H1 with the ionization energy of about 0.85eV. In thick GaN layers grown by hydride vapor phase epitaxy (HVPE) or in bulk GaN grown by some other techniques, the green luminescence (GL) band with a maximum at 2.4eV is the dominant PL band. The GL band and the YL band in these samples are attributed to two charge states of the CN defect. The blue luminescence band with a maximum at 2.9eV in undoped and Zn-doped GaN grown by HVPE or MOCVD is attributed to the ZnGa acceptor. The GL2 band observed in high-resistivity GaN samples at 2.35eV is caused by an internal transition at the VN defect. The VGaON defect is present with high concentrations in n-type GaN and can be detected by PAS and optical DLTS. Most likely, it is a nonradiative defect and cannot be detected by PL.


      PubDate: 2015-02-25T01:28:55Z
       
  • Analytical Techniques for Electrically Active Defect Detection
    • Abstract: Publication date: Available online 21 February 2015
      Source:Semiconductors and Semimetals
      Author(s): E. Simoen , J. Lauwaert , H. Vrielinck
      This chapter aims to review analytical techniques for the detection of electrically active defects in semiconductor materials. In all cases, the operation principles, the strengths, and the weaknesses will be outlined and illustrated for state-of-the-art examples. Based on the impact of deep level defects on the main semiconductor parameters (resistivity, carrier lifetime, fixed space charge, etc.,) one can define different analysis methods: from simple resistivity measurements to more spectroscopic-like techniques, relying on capacitance or current transients obtained after applying bias or optical pulses to a diode structure. While in the pioneering days, Hall effect versus temperature was the technique of reference for deep level studies in silicon and germanium, nowadays, deep level transient spectroscopy is the standard, with high sensitivity for small relative concentrations of defects. In some cases, complementary information can be gathered from admittance spectroscopy, revealing also details on shallow levels in the band gap. However, it turns out that in many practical cases, the carrier lifetime and related device characteristics (generation and recombination current) are more sensitive than the spectroscopic techniques. The possibility for applying these techniques to nanometric structures will be discussed, eventually resulting in what can be considered as single-defect spectroscopies.


      PubDate: 2015-02-25T01:28:55Z
       
  • Nanoindentation of Silicon and Germanium
    • Abstract: Publication date: Available online 18 February 2015
      Source:Semiconductors and Semimetals
      Author(s): M.S.R.N. Kiran , B. Haberl , J.E. Bradby , J.S. Williams
      Nanoindentation of silicon and germanium is of interest not only for the measurement of their mechanical properties but more importantly for the fact that they undergo a series of phase transformations under applied pressure. Indeed, after complete pressure release, the material does not return to the starting diamond cubic phase, but several metastable phases are possible, depending on the indentation conditions. In silicon, both crystalline (diamond cubic) and amorphous phases undergo a phase transformation to a dense metallic phase at around 11GPa, a deformation process that defines the hardness of these materials. On pressure release, either a mixture of a rhombohedral (r8) phase and a body-centered cubic (bc8) phase or a pressure-induced amorphous silicon structure results. The mixed r8/bc8 phase is stable to 200°C and has been shown to have properties of a narrow bandgap semiconductor and can be doped both n- and p-type. In germanium, the deformation processes under indentation are more complex with both plastic deformation by slip and twinning as well as phase transformation observed for diamond cubic germanium, depending on the indentation conditions. Amorphous germanium is easier to phase transform since slip-induced processes are avoided. Both crystalline and amorphous forms of germanium can be transformed to a high-density metallic phase under pressure, but several different transformation pathways are possible on pressure release, with the r8, hexagonal diamond and simple tetragonal end phases obtained under specific conditions. These deformation and phase transformation processes under indentation are reviewed in this chapter and compared with the behavior of these materials under diamond anvil cell pressure.


      PubDate: 2015-02-19T07:29:56Z
       
  • Surface and Defect States in Semiconductors Investigated by Surface
           Photovoltage
    • Abstract: Publication date: Available online 18 February 2015
      Source:Semiconductors and Semimetals
      Author(s): Daniela Cavalcoli , Beatrice Fraboni , Anna Cavallini
      The aim of this chapter is a throughout description and discussion of surface photovoltage spectroscopy. The basic physical principles, experimental details, and relevant results of the method are described, and the capability of the method to extract material properties like optical band gap and defect-related states is discussed. The method presents several advantages, as it allows for the identification of conduction versus valence band nature of the defect-related transitions and the defect level positions within the band gap. Moreover, it allows for the detection of relatively low densities of surface defects as well as their cross-sections. The application of the method to different materials and structures is discussed, ranging from bulk semiconductors to low-dimensional systems, to nanostructures.


      PubDate: 2015-02-19T07:29:56Z
       
  • Defective Solid-Phase Epitaxial Growth of Si
    • Abstract: Publication date: Available online 18 February 2015
      Source:Semiconductors and Semimetals
      Author(s): N.G. Rudawski , A.G. Lind , T. Martin
      The solid-phase epitaxial growth (SPEG) process of Si (interchangeably referred to as solid-phase epitaxial regrowth, solid-phase epitaxial recrystallization, solid-phase epitaxy, and solid-phase epitaxial crystallization) is the epitaxial crystallization of an amorphous (α) layer of Si in direct contact with a single-crystal Si substrate (wafer). Most commonly, this process is considered within the context of ion-implanting a single-crystal substrate to generate the α-Si layer. Ideally, the SPEG process is perfect in that the initial α-Si layer crystallizes into a perfect single crystal with the same orientation as the substrate. However, the process is often far from ideal and the crystallized layer often contains defects as a result of SPEG. Here, the origins and understanding of the defects associated with the SPEG process are reviewed. Initially, the case of a starting α-Si layer that is infinite along the two in-plane directions of the wafer, but finite along the wafer normal direction is considered. The effects if α/crystalline (growth) interface roughness, “burying” of the α-Si layer below the wafer surface, substrate orientation, impurities, and externally applied stress on defectiveness of the SPEG process are discussed within this context. Subsequently, defects resulting from SPEG in laterally confined structures are considered. Specifically, this includes structures when the initial growth interface terminates at a SiO x -filled region (trench) on one or two sides structures defined by masking. In all cases, transmission electron microscopy is used to analyze the nature of the defects.


      PubDate: 2015-02-19T07:29:56Z
       
 
 
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