We present a comprehensive, up-to-date compilation of band parameters for the technologically important III–V zinc blende and wurtzite compound semiconductors: GaAs, GaSb, GaP, GaN, AlAs, AlSb, AlP, AlN, InAs, InSb, InP, and InN, along with their ternary and quaternary alloys. Based on a review of the existing literature, complete and consistent parameter sets are given for all materials. Emphasizing the quantities required for band structure calculations, we tabulate the direct and indirect energy gaps, spin-orbit, and crystal-field splittings, alloy bowing parameters, effective masses for electrons, heavy, light, and split-off holes, Luttinger parameters, interband momentum matrix elements, and deformation potentials, including temperature and alloy-composition dependences where available. Heterostructure band offsets are also given, on an absolute scale that allows any material to be aligned relative to any other.

Band parameters for III–V compound semiconductors and their alloys

Boron-doped silicon nanowires (SiNWs) were used to create highly sensitive, real-time electrically based sensors for biological and chemical species. Amine- and oxide-functionalized SiNWs exhibit pH-dependent conductance that was linear over a large dynamic range and could be understood in terms of the change in surface charge during protonation and deprotonation. Biotin-modified SiNWs were used to detect streptavidin down to at least a picomolar concentration range. In addition, antigen-functionalized SiNWs show reversible antibody binding and concentration-dependent detection in real time. Lastly, detection of the reversible binding of the metabolic indicator Ca2+ was demonstrated. The small size and capability of these semiconductor nanowires for sensitive, label-free, real-time detection of a wide range of chemical and biological species could be exploited in array-based screening and in vivo diagnostics.

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Nanowire Nanosensors for Highly Sensitive and Selective Detection of Biological and Chemical Species

We present a comprehensive and up-to-date compilation of band parameters for all of the nitrogen-containing III–V semiconductors that have been investigated to date. The two main classes are: (1) “conventional” nitrides (wurtzite and zinc-blende GaN, InN, and AlN, along with their alloys) and (2) “dilute” nitrides (zinc-blende ternaries and quaternaries in which a relatively small fraction of N is added to a host III–V material, e.g., GaAsN and GaInAsN). As in our more general review of III–V semiconductor band parameters [I. Vurgaftman et al., J. Appl. Phys. 89, 5815 (2001)], complete and consistent parameter sets are recommended on the basis of a thorough and critical review of the existing literature. We tabulate the direct and indirect energy gaps, spin-orbit and crystal-field splittings, alloy bowing parameters, electron and hole effective masses, deformation potentials, elastic constants, piezoelectric and spontaneous polarization coefficients, as well as heterostructure band offsets. Temperature an...

Band parameters for nitrogen-containing semiconductors

Atomic layer deposition(ALD), a chemical vapor deposition technique based on sequential self-terminating gas–solid reactions, has for about four decades been applied for manufacturing conformal inorganic material layers with thickness down to the nanometer range. Despite the numerous successful applications of material growth by ALD, many physicochemical processes that control ALD growth are not yet sufficiently understood. To increase understanding of ALD processes, overviews are needed not only of the existing ALD processes and their applications, but also of the knowledge of the surface chemistry of specific ALD processes. This work aims to start the overviews on specific ALD processes by reviewing the experimental information available on the surface chemistry of the trimethylaluminum/water process. This process is generally known as a rather ideal ALD process, and plenty of information is available on its surface chemistry. This in-depth summary of the surface chemistry of one representative ALD process aims also to provide a view on the current status of understanding the surface chemistry of ALD, in general. The review starts by describing the basic characteristics of ALD, discussing the history of ALD—including the question who made the first ALD experiments—and giving an overview of the two-reactant ALD processes investigated to date. Second, the basic concepts related to the surface chemistry of ALD are described from a generic viewpoint applicable to all ALD processes based on compound reactants. This description includes physicochemical requirements for self-terminating reactions,reaction kinetics, typical chemisorption mechanisms, factors causing saturation, reasons for growth of less than a monolayer per cycle, effect of the temperature and number of cycles on the growth per cycle (GPC), and the growth mode. A comparison is made of three models available for estimating the sterically allowed value of GPC in ALD. Third, the experimental information on the surface chemistry in the trimethylaluminum/water ALD process are reviewed using the concepts developed in the second part of this review. The results are reviewed critically, with an aim to combine the information obtained in different types of investigations, such as growth experiments on flat substrates and reaction chemistry investigation on high-surface-area materials. Although the surface chemistry of the trimethylaluminum/water ALD process is rather well understood, systematic investigations of the reaction kinetics and the growth mode on different substrates are still missing. The last part of the review is devoted to discussing issues which may hamper surface chemistry investigations of ALD, such as problematic historical assumptions, nonstandard terminology, and the effect of experimental conditions on the surface chemistry of ALD. I hope that this review can help the newcomer get acquainted with the exciting and challenging field of surface chemistry of ALD and can serve as a useful guide for the specialist towards the fifth decade of ALD research.

Surface chemistry of atomic layer deposition: A case study for the trimethylaluminum/water process

and Fuels Changzhi Li,† Xiaochen Zhao,† Aiqin Wang,† George W. Huber,†,‡ and Tao Zhang*,† †State Key Laborotary of Catalysis, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China ‡Department of Chemical and Biological Engineering, University of WisconsinMadison, Madison, Wisconsin 53706, United States

Catalytic Transformation of Lignin for the Production of Chemicals and Fuels

We have employed photoluminescence spectroscopy to determine the interdiffusion of Al and Ga in (Al,Ga)As/GaAs quantum wells. The luminescence due to the n=l electron to heavy hole transition in these wells before and after anneal was measured. A variational calculation was employed to determine the expected position of this luminescence peak both before and after the anneal. A single diffusion coefficient, D , was used to model the interdiffusion of the Al and Ga and from the shifted position of the luminescence peaks under various anneal conditions of time and temperature its value was determined. These measurements were performed as a function of temperature to yield ΔE where D = D 0 e -ΔE/KT. This diffusion coefficient was also studied as a function of the initial Al composition in the cladding layers which ranged from 0.3 to 1.0.

Interdiffusion of Al and Ga in (Al,Ga)As/GaAs Quantum Wells

Solid-phase epitaxy (SPE) and other three-dimensional epitaxial crystallization processes pose challenging structural and chemical characterization problems. The concentration of defects, the spatial distribution of elastic strain, and the chemical state of ions each vary with nanoscale characteristic length scales and depend sensitively on the gas environment and elastic boundary conditions during growth. The lateral or three-dimensional propagation of crystalline interfaces in SPE has nanoscale or submicrometer characteristic distances during typical crystallization times. An in situ synchrotron hard x-ray instrument allows these features to be studied during deposition and crystallization using diffraction, resonant scattering, nanobeam and coherent diffraction imaging, and reflectivity. The instrument incorporates a compact deposition system allowing the use of short-working-distance x-ray focusing optics. Layers are deposited using radio-frequency magnetron sputtering and evaporation sources. The deposition system provides control of the gas atmosphere and sample temperature. The sample is positioned using a stable mechanical design to minimize vibration and drift and employs precise translation stages to enable nanobeam experiments. Results of in situ x-ray characterization of the amorphous thin film deposition process for a SrTiO3/BaTiO3 multilayer illustrate implementation of this instrument.

Instrument for in situ hard x-ray nanobeam characterization during epitaxial crystallization and materials transformations.

The metal-organic vapor phase epitaxy (MOVPE) technique is perhaps themost versatile of the conventional III–V growth epitaxial systems. This versatility stems from the wide variety of chemical precursors available for the growth and doping of the films. Two examples of this versatility, carbon doping and selective epitaxy, are presented. Future progress within this technology will continue to be driven by the development of new chemistries.

New Growth Chemistries and Techniques in Metal-Organic Vapor Phase Epitaxy

Step-graded InGaP y Sb 1−y and In x Ga 1−x As metamorphic buffer layer (MBL) structures are grown on GaAs substrates by metal-organic chemical vapor deposition (MOCVD). AFM analysis indicates that graded group V InGaP y Sb 1−y MBLs exhibit significantly lower surface roughness (∼4.7nm) compared with more conventional graded group III In x Ga 1−x As MBLs, which typically have rms surface roughness in the range of 7–14nm. To reduce the surface roughness of the In x Ga 1−x As MBL, a post growth Chemical-Mechanical Polishing (CMP) procedure is implemented. AFM image analysis indicates the CMP process is effective in reducing the step-graded In x Ga 1−x As MBL surface roughness from ∼7.3 nm (as-grown) to 2.3 nm post CMP. Preliminary studies indicate that bulk InGaAs layers regrown on top of the MBL subjected to CMP exhibit improved static and transient PL characteristics compared with those deposited on as-grown MBLs.

https://ieeexplore.ieee.org/iel5/5963766/5978276/05978326.pdf

Characteristics of step-graded In x Ga 1−x As and InGaP y Sb 1−y metamorphic buffer layers on GaAs substrates

A method of making a single crystal Ga*N article (10), including the steps of: providing a substrate (20) of crystalline material having a surface (16) which is epitaxially compatible with Ga*N; depositing a layer of single crystal Ga*N (26) over the surface of the substrate; and etchably removing the substrate from the layer of single crystal Ga*N, to yield the layer of single crystal Ga*N as said single crystal Ga*N article. The invention is an article aspect relates to bulk single crystal Ga*N articles, such as are suitable for use as a substrate for the fabrication of microelectronic structures thereon, and to microelectronic devices comprising bulk single crystal Ga*N substrates, and their precursor structures.

Thomas F. Kuech

Papers

Interdiffusion of Al and Ga in (Al,Ga)As/GaAs Quantum Wells

Instrument for in situ hard x-ray nanobeam characterization during epitaxial crystallization and materials transformations.

New Growth Chemistries and Techniques in Metal-Organic Vapor Phase Epitaxy

Characteristics of step-graded In x Ga 1−x As and InGaP y Sb 1−y metamorphic buffer layers on GaAs substrates

Method of making single crystal gallium nitride