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

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

/pdf/the-observation-of-gravitational-waves-from-a-binary-black-58srpupgg9.pdf

The Observation of Gravitational Waves from a Binary Black Hole Merger

The diffraction tomography theorem is adapted to one-dimensional length measurement. The resulting spectral interferometry technique is described and the first length measurements using this technique on a model eye and on a human eye in vivo are presented.

Measurement of intraocular distances by backscattering spectral interferometry

Industries such as the automotive, aerospace or military, as well as environmental and biological research have promoted the development of ultraviolet (UV) photodetectors capable of operating at high temperatures and in hostile environments. UV-enhanced Si photodiodes are hence giving way to a new generation of UV detectors fabricated from wide-bandgap semiconductors, such as SiC, diamond, III-nitrides, ZnS, ZnO, or ZnSe. This paper provides a general review of latest progresses in wide-bandgap semiconductor photodetectors.

https://iopscience.iop.org/article/10.1088/0268-1242/18/4/201/pdf

Wide-bandgap semiconductor ultraviolet photodetectors

Surface integrity in material removal processes: Recent advances

This paper presents a detailed analysis of the stressing mechanisms for highly rugged low-noise GaN monolithic-microwave integrated-circuit amplifiers operated at extremely high input powers. As an example, a low-noise amplifier (LNA) operating in the 3-7-GHz frequency band is used. A noise figure (NF) below 2.3 dB is measured from 3.5 to 7 GHz with NF<1.8 dB between 5-7 GHz. This device survived 33 dBm of available RF input power for 16 h without any change in low-noise performance. The stress mechanisms at high input powers are identified by systematic measurements of an LNA and a single high electron-mobility transistor in the frequency and time domains. It is shown that the gate dc current, which occurs due to self-biasing, is the most critical factor regarding survivability. A series resistance in the gate dc feed can reduce this gate current by feedback, and may be used to improve LNA ruggedness

Analysis of the Survivability of GaN Low-Noise Amplifiers

GaN-based high-electron mobility transistors with planar multiple grating field plates (MGFPs) for high-voltage operation are described. A synergy effect with additional electron channel confinement by using a heterojunction AlGaN back barrier (BB) is demonstrated. Suppression of the OFF-state subthreshold gate and drain leakage currents enables breakdown voltage enhancement over 700 V and a low ON-state resistance of 0.68 mΩ × cm2. Such devices have a minor tradeoff in ON-state resistance, lag factor, maximum oscillation frequency, and cutoff frequency. A systematic study of the MGFP design and the effect of Al composition in the BB is described. Physics-based device simulation results give insight into electric field distribution and charge carrier concentration, depending on the field plate design.

AlGaN/GaN/AlGaN DH-HEMTs Breakdown Voltage Enhancement Using Multiple Grating Field Plates (MGFPs)

High-power quantum well lasers with high brightness in the spectral range between 650 nm and 1080 nm will be presented. Improved layer structures with a narrow vertical far-field divergence down to angles of 15deg (full-width at half-maximum) were developed. For these layer structures, optimized tapered lasers were processed to achieve laterally a nearly diffraction-limited beam quality with beam propagation factors smaller than 2. Depending on the emission wavelength, the tapered devices reach an output power up to 12 W and a brightness of 1 GWmiddotcm-2middotsr-1.

High-Brightness Quantum Well Tapered Lasers

GaAs/AlGaAs single quantum well samples have been investigated by photoluminescence spectroscopy using a probe size of about a micron at low temperature. Thin quantum wells fabricated by molecular beam epitaxy with growth interruptions at the interfaces reveal intense photoluminescence lines with spectral widths below 0.1 meV at the low‐energy side of the main luminescence. Mapping the quantum well by scanning the probe shows local emission of these sharp lines, which change in number and in energy with lateral probe position. The local source of the sharp lines, as well as their temperature and saturation behavior shows that they are caused by single excitons localized at sample inhomogeneities, like GaAs well width fluctuations.

Günther Tränkle

Papers

Analysis of the Survivability of GaN Low-Noise Amplifiers

AlGaN/GaN/AlGaN DH-HEMTs Breakdown Voltage Enhancement Using Multiple Grating Field Plates (MGFPs)

High-Brightness Quantum Well Tapered Lasers

Sharp-line photoluminescence of excitons localized at GaAs/AlGaAs quantum well inhomogeneities

Femtosecond carrier dynamics in GaAs far from equilibrium.