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

https://is.muni.cz/el/1431/podzim2006/C7780/um/Read/2711172/SAM_str_grwth_ProgSurfSci00_151.pdf

Structure and growth of self-assembling monolayers

Gallium oxide (Ga2O3) is emerging as a viable candidate for certain classes of power electronics, solar blind UV photodetectors, solar cells, and sensors with capabilities beyond existing technologies due to its large bandgap. It is usually reported that there are five different polymorphs of Ga2O3, namely, the monoclinic (β-Ga2O3), rhombohedral (α), defective spinel (γ), cubic (δ), or orthorhombic (e) structures. Of these, the β-polymorph is the stable form under normal conditions and has been the most widely studied and utilized. Since melt growth techniques can be used to grow bulk crystals of β-GaO3, the cost of producing larger area, uniform substrates is potentially lower compared to the vapor growth techniques used to manufacture bulk crystals of GaN and SiC. The performance of technologically important high voltage rectifiers and enhancement-mode Metal-Oxide Field Effect Transistors benefit from the larger critical electric field of β-Ga2O3 relative to either SiC or GaN. However, the absence of clear demonstrations of p-type doping in Ga2O3, which may be a fundamental issue resulting from the band structure, makes it very difficult to simultaneously achieve low turn-on voltages and ultra-high breakdown. The purpose of this review is to summarize recent advances in the growth, processing, and device performance of the most widely studied polymorph, β-Ga2O3. The role of defects and impurities on the transport and optical properties of bulk, epitaxial, and nanostructures material, the difficulty in p-type doping, and the development of processing techniques like etching, contact formation, dielectrics for gate formation, and passivation are discussed. Areas where continued development is needed to fully exploit the properties of Ga2O3 are identified.

A review of Ga2O3 materials, processing, and devices

We have resolved single-exponential relaxation dynamics of the 2-, 3-, and 4-electron-hole pair states in nearly monodisperse cadmium selenide quantum dots with radii ranging from 1 to 4 nanometers. Comparison of the discrete relaxation constants measured for different multiple-pair states indicates that the carrier decay rate is cubic in carrier concentration, which is characteristic of an Auger process. We observe that in the quantum-confined regime, the Auger constant is strongly size-dependent and decreases with decreasing the quantum dot size as the radius cubed.

https://science.sciencemag.org/content/sci/287/5455/1011.full.pdf

Quantization of multiparticle auger rates in semiconductor quantum dots

http://nathan.instras.com/documentDB/paper-69.pdf

Porous silicon: a quantum sponge structure for silicon based optoelectronics

HgTe colloidal quantum dots are synthesized with high monodispersivity with sizes up to ∼15 nm corresponding to a room temperature absorption edge at ∼5 μm. The shape is tetrahedral for larger sizes and up to five peaks are seen in the absorption spectra with a clear size dependence. The size range of the HgTe quantum dots is extended to ∼20 nm using regrowth. The corresponding room temperature photoluminescence and absorption edge reach into the long-wave infrared, past 8 μm. Upon cooling to liquid nitrogen temperature, a photoconductive response is obtained in the long-wave infrared region up to 12 μm. Configuration-interaction tight-binding calculations successfully explain the spectra and the size dependence. The five optical features can be assigned to sets of single hole to single electron transitions whose strengths are strongly influenced by the multiband/multiorbital character of the quantum-dot electronic states.

Mercury Telluride Colloidal Quantum Dots: Electronic Structure, Size-Dependent Spectra, and Photocurrent Detection up to 12 μm

The notion and usefulness of the effective dielectric constant in silicon nanocrystallites are analyzed using a self-consistent linear screening calculation of hydrogenic impurities. It is shown that the self-consistent screened potential induced by the defects can be reasonably approximated by the classical electrostatics expression of the Coulomb potential because the impurity energy levels are dominated by the surface polarization effects. The impurity binding energy, the exciton binding energy, and the exchange splitting are estimated taking into account the modified dielectric properties of the crystallites. The consequences of charging effects on carrier injection are discussed and shown to be important.

Hydrogenic impurity levels, dielectric constant, and Coulomb charging effects in silicon crystallites

Theoretical and experimental results are presented providing evidence for fast Auger recombination in silicon nanocrystallites. Calculations give nonradiative lifetimes in the 1 ns range. Luminescence experiments on porous silicon exhibit a saturation at high excitation power. The Auger effect gives a natural explanation for this saturation as well as for the recently observed quenching of the photoluminescence and voltage tunable electroluminescence. In this last case the importance of Coulomb charging effects is shown to be at the origin of the linewidth. The consequences of such fast Auger recombination for the optical efficiency of indirect band-gap semiconductor nanocrystallites are discussed.

Auger and Coulomb charging effects in semiconductor nanocrystallites.

Colloidal quantum dots (QDs) raise more and more interest as solution-processable and tunable optical gain materials. However, especially for infrared active QDs, optical gain remains inefficient. Since stimulated emission involves multifold degenerate band-edge states, population inversion can be attained only at high pump power and must compete with efficient multi-exciton recombination. Here, we show that mercury telluride (HgTe) QDs exhibit size-tunable stimulated emission throughout the near-infrared telecom window at thresholds unmatched by any QD studied before. We attribute this unique behaviour to surface-localized states in the bandgap that turn HgTe QDs into 4-level systems. The resulting long-lived population inversion induces amplified spontaneous emission under continuous-wave optical pumping at power levels compatible with solar irradiation and direct current electrical pumping. These results introduce an alternative approach for low-threshold QD-based gain media based on intentional trap states that paves the way for solution-processed infrared QD lasers and amplifiers.

/pdf/continuous-wave-infrared-optical-gain-and-amplified-2n37x0yh56.pdf

G. Allan

Papers

Mercury Telluride Colloidal Quantum Dots: Electronic Structure, Size-Dependent Spectra, and Photocurrent Detection up to 12 μm

Hydrogenic impurity levels, dielectric constant, and Coulomb charging effects in silicon crystallites

Auger and Coulomb charging effects in semiconductor nanocrystallites.

Continuous-wave infrared optical gain and amplified spontaneous emission at ultralow threshold by colloidal HgTe quantum dots.

Electronic properties of antimony chalcogenides.