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

Carrier concentration profiles of two-dimensional electron gases are investigated in wurtzite, Ga-face AlxGa1−xN/GaN/AlxGa1−xN and N-face GaN/AlxGa1−xN/GaN heterostructures used for the fabrication of field effect transistors. Analysis of the measured electron distributions in heterostructures with AlGaN barrier layers of different Al concentrations (0.15<x<0.5) and thickness between 20 and 65 nm demonstrate the important role of spontaneous and piezoelectric polarization on the carrier confinement at GaN/AlGaN and AlGaN/GaN interfaces. Characterization of the electrical properties of nominally undoped transistor structures reveals the presence of high sheet carrier concentrations, increasing from 6×1012 to 2×1013 cm−2 in the GaN channel with increasing Al-concentration from x=0.15 to 0.31. The observed high sheet carrier concentrations and strong confinement at specific interfaces of the N- and Ga-face pseudomorphic grown heterostructures can be explained as a consequence of interface charges induced by ...

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Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N- and Ga-face AlGaN/GaN heterostructures

Wide bandgap semiconductors are extremely attractive for the gamut of power electronics applications from power conditioning to microwave transmitters for communications and radar. Of the various materials and device technologies, the AlGaN/GaN high-electron mobility transistor seems the most promising. This paper attempts to present the status of the technology and the market with a view of highlighting both the progress and the remaining problems.

AlGaN/GaN HEMTs-an overview of device operation and applications

Materials research plays a vital role in transforming breakthrough scientific ideas into next-generation technology. Similar to the way silicon revolutionized the microelectronics industry, the proper materials can greatly impact the field of plasmonics and metamaterials. Currently, research in plasmonics and metamaterials lacks good material building blocks in order to realize useful devices. Such devices suffer from many drawbacks arising from the undesirable properties of their material building blocks, especially metals. There are many materials, other than conventional metallic components such as gold and silver, that exhibit metallic properties and provide advantages in device performance, design flexibility, fabrication, integration, and tunability. This review explores different material classes for plasmonic and metamaterial applications, such as conventional semiconductors, transparent conducting oxides, perovskite oxides, metal nitrides, silicides, germanides, and 2D materials such as graphene. This review provides a summary of the recent developments in the search for better plasmonic materials and an outlook of further research directions.

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Alternative Plasmonic Materials: Beyond Gold and Silver

The role of extended and point defects, and key impurities such as C, O, and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation, and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes, and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.

Gan : processing, defects, and devices

We have demonstrated GaN microstructures formed by polarity-selective chemical etching in KOH solution. It was found that KOH selectively etches N-polar GaN but not Ga-polar GaN. The polarity-patterned GaN was grown by plasma-assisted molecular beam epitaxy. For intermediate etching times, hexagonal GaN pyramids were formed in the N-polar regions. With prolonged etching, the N-polar GaN can be completely removed. A one-dimensional array of GaN stripes and a two-dimensional array of hexagonal holes formed in a GaN matrix have been fabricated. Extremely smooth vertical sidewalls have been achieved along with an etch depth of up to 4 µm.

https://iopscience.iop.org/article/10.1143/JJAP.42.L1405/pdf

Patterning GaN Microstructures by Polarity-Selective Chemical Etching

We report on the growth and transport characteristics of high-density (∼1013 cm−2) two-dimensional electron gases confined at the AlGaN/GaN interface grown by plasma-assisted molecular-beam epitaxy on sapphire substrates. For structures consisting of a 25 nm Al0.30Ga0.70N barrier deposited on a 2 μm insulating GaN buffer, room-temperature mobilities averaging 1400 cm2/V s at a sheet charge density of 1.0×1013 cm−2 are consistently achieved. Central to our approach is a sequence of two Ga/N ratios during the growth of the insulating GaN buffer layer. The two-step buffer layer allows us to simultaneously optimize the reduction of threading dislocations and surface morphology. Our measured sheet resistivities as low as 350Ω/□ compare favorably with those achieved on sapphire or SiC by any growth method. Representative current–voltage characteristics of high-electron-mobility transistors fabricated from this material are presented.

http://manfragroup.org/wp-content/uploads/2014/12/Dislocation-and-morphology-control-during-molecular-beam-epitaxy-of-AlGaN-GaN-heterostructures-directly-on-sapphire-substrates.pdf

Dislocation and morphology control during molecular-beam epitaxy of AlGaN/GaN heterostructures directly on sapphire substrates

Return-to-zero differential phase-shift keying applications require a differential amplifier with high bandwidth, high gain, low noise, and good input impedance match. In this paper, we describe an InGaAs-InP heterostructure bipolar transistor differential transimpedance amplifier with high bandwidth of 47 GHz and high gain of 56 dB-/spl Omega/. The input-referred current noise is less than 35 pA//spl radic/Hz over the measurement range up to 40 GHz.

An InGaAs-InP HBT differential transimpedance amplifier with 47-GHz bandwidth

An optical receiver has a monolithically integrated electrical and optical circuit that includes a substrate with a planar surface. Along the planar surface, the monolithically integrated electrical and optical circuit has an optical hybrid, one or more variable optical attenuators, and photodetectors. The optical hybrid is connected to receive light beams, to interfere light of said received light beams with a plurality of relative phases and to output said interfered light via optical outputs thereof. Each of the one or more variable optical attenuators connects between a corresponding one of the optical outputs and a corresponding one of the photodetectors.

Monolithic coherent optical detectors

High electron mobility transistors (HEMTs) are fabricated from AlGaN-GaN heterostructures grown by plasma-assisted molecular beam epitaxy (MBE) on semi-insulating 6H-SiC substrates. At a sheet charge density of 1.3 /spl times/ 10/sup 13/ cm/sup -2/, we have repeatedly obtained electron mobilities in excess of 1350 cm/sup 2//Vs. HEMT devices with a gate length of 1/spl mu/m, a gate width of 200 /spl mu/m, and a source-drain spacing of 5 /spl mu/m show a maximum drain current of 1.1 A/mm and a peak transconductance of 125 mS/mm. For unpassivated HEMTs, we measured a saturated power output of 8.2-W/mm continuous wave (cw) at 2 GHz with an associated gain of 11.2 dB and a power-added efficiency of 41%. The achievement of high-power operation without a surface passivation layer suggests that free surface may not be the dominant source of radio-frequency (RF) dispersion in these MBE-grown structures. This data may help discriminate between possible physical mechanisms of RF dispersion in AlGaN-GaN HEMTs grown by different techniques.

http://manfragroup.org/wp-content/uploads/2014/12/Unpassivated-AlGaN-GaN-HEMTs-with-minimal-RF-dispersion-grown-by-plasma-assisted-MBE-on-semi-insulating-6H-SiC-substrates.pdf

Nils Weimann

Papers

Patterning GaN Microstructures by Polarity-Selective Chemical Etching

Dislocation and morphology control during molecular-beam epitaxy of AlGaN/GaN heterostructures directly on sapphire substrates

An InGaAs-InP HBT differential transimpedance amplifier with 47-GHz bandwidth

Monolithic coherent optical detectors

Unpassivated AlGaN-GaN HEMTs with minimal RF dispersion grown by plasma-assisted MBE on semi-insulating 6H-SiC substrates