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

Materials with nanoscopic dimensions not only have potential technological applications in areas such as device technology and drug delivery but also are of fundamental interest in that the properties of a material can change in this regime of transition between the bulk and molecular scales. In this article, a relatively new method for preparing nanomaterials, membrane-based synthesis, is reviewed. This method entails synthesis of the desired material within the pores of a nanoporous membrane. Because the membranes used contain cylindrical pores of uniform diameter, monodisperse nanocylinders of the desired material, whose dimensions can be carefully controlled, are obtained. This "template" method has been used to prepare polymers, metals, semiconductors, and other materials on a nanoscopic scale.

https://science.sciencemag.org/content/sci/266/5193/1961.full.pdf

Nanomaterials: a membrane-based synthetic approach.

Nanosphere lithography (NSL) is an inexpensive, simple to implement, inherently parallel, high throughput, materials general nanofabrication technique capable of producing an unexpectedly large variety of nanoparticle structures and well-ordered 2D nanoparticle arrays. This article describes our recent efforts to broaden the scope of NSL to include strategies for the fabrication of several new nanoparticle structural motifs and their characterization by atomic force microscopy. NSL has also been demonstrated to be well-suited to the synthesis of size-tunable noble metal nanoparticles in the 20−1000 nm range. This characteristic of NSL has been especially valuable for investigating the fascinating richness of behavior manifested in size-dependent nanoparticle optics. The use of localized surface plasmon resonance (LSPR) spectroscopy to probe the size-tunable optical properties of Ag nanoparticles and their sensitivity to the local, external dielectric environment (viz., the nanoenvironment) is discussed in...

Nanosphere Lithography: A Versatile Nanofabrication Tool for Studies of Size-Dependent Nanoparticle Optics

Random-matrix theories in quantum physics : common concepts

The transport properties of disordered solids have been the subject of much work since at least the 1950s, but with a new burst of activity during the 1980s which has survived up to the present day. There have been numerous reviews of a more or less specialized nature. The present review aims to fill the niche for a non-specialized review of this very active area of research. The basic concepts behind the theory are introduced with more detailed sections covering experimental results, one-dimensional localization, scaling theory, weak localization, magnetic field effects and fluctuations.

https://iopscience.iop.org/article/10.1088/0034-4885/56/12/001/pdf

Localization: theory and experiment

Structures in which electrons are confined to move in two dimensions (quantum wells) have led to new physical discoveries and technological applications. Modification of these structures to confine the electrons to one dimension (quantum wires) or release them in the third dimension, are predicted to lead to new electrical and optical properties. This article discusses techniques to make quantum wires, and quantum wells of controlled size and shape, from compound semiconductor materials, and describes some of the properties of these structures.

https://science.sciencemag.org/content/sci/254/5036/1326.full.pdf

New Quantum Structures

We present experimental studies of energy loss from quasi-two-dimensional electron gases that are driven to a nonequilibrium steady state by intense, ultrahigh-frequency fields. For the ${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As/GaAs heterostructures studied, longitudinal-optical (LO) phonon emission dominates energy loss across the previously unexplored frequency range from 0.2 to 3.5 THz, at moderate electron temperatures. We find an unexpected resonance in the absorbed power that is consistent with an increase near 0.5 THz in either the net LO phonon emission rate, or in the high-frequency mobility.

Resonant-energy relaxation of terahertz-driven two-dimensional electron gases

Resonant harmonic generation and dynamic screening in a double quantum well.

We introduce two methods of extracting the rate of loss of electron phase coherence in ballistic quantum dot microstructures from statistical measures of magnetic-field-induced conductance fluctuation. The first method uses changes in the (magnetic-field) power spectrum of conductance fluctuations upon changing the average conductance through the dot. The second, based on a Hauser-Feshbach--like formula from nuclear physics, relates the phase-breaking rate to the amplitude of the conductance fluctuations. The two methods are then applied to experimental data from GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As quantum dots in the shape of a stadium billiard. Preliminary results give phase-breaking rates that are consistent with those previously found in quasiballistic GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As microstructures.

Phase breaking in ballistic quantum dots: Experiment and analysis based on chaotic scattering.

We have experimentally measured the 1--2 intersubband absorption in a single 40 nm wide modulation-doped ${\mathrm{Al}}_{0.3}{\mathrm{Ga}}_{0.7}\mathrm{As}/\mathrm{GaAs}$ square quantum well as a function of frequency, intensity, and charge density. The low-intensity depolarization-shifted absorption occurs near $80{\mathrm{cm}}^{\ensuremath{-}1}$ (10 meV or 2.4 THz), nearly 30% higher than the intersubband spacing. At higher intensities, the absorption peak shifts to lower frequencies. Our data are in good agreement with a theory proposed by Za\l{}u\ifmmode \dot{z}\else \.{z}\fi{}ny, which attributes the redshift to a reduction in the depolarization shift as the excited subband becomes populated.

P. F. Hopkins

Papers

New Quantum Structures

Resonant-energy relaxation of terahertz-driven two-dimensional electron gases

Resonant harmonic generation and dynamic screening in a double quantum well.

Phase breaking in ballistic quantum dots: Experiment and analysis based on chaotic scattering.

Undressing a collective intersubband excitation in a quantum well.