Investigation of AlInN HEMT structures with different AlGaN buffer layers grown on sapphire substrates by MOCVD

Abstract

Cataloged from PDF version of article.We investigate the structural and electrical properties of AlxIn1-xN/AlN/GaN heterostructures with AlGaN buffers grown by MOCVD, which can be used as an alternative to AlInN HEMT structures with GaN buffer. The effects of the GaN channel thickness and the addition of a content graded AlGaN layer to the structural and electrical characteristics were studied through variable temperature Hall effect measurements, high resolution XRD, and AFM measurements. Enhancement in electron mobility was observed in two of the suggested AlxIn1-xN/AlN/GaN/Al0.04Ga0.96N heterostructures when compared to the standard AlxIn1-xN/AlN/GaN heterostructure. This improvement was attributed to better electron confinement in the channel due to electric field arising from piezoelectric polarization charge at the Al0.04Ga0.96N/GaN heterointerface and by the conduction band discontinuity formed at the same interface. If the growth conditions and design parameters of the AlxIn1-xN HEMT structures with AlGaN buffers can be modified further, the electron spillover from the GaN channel can be significantly limited and even higher electron mobilities, which result in lower two-dimensional sheet resistances, would be possible. (C) 2012 Elsevier B.V. All rights reserved

An analytical model for the current voltage characteristics of GaN-capped AlGaN/GaN and AlInN/GaN HEMTs including thermal and self-heating effects

“…High electron mobility transistors (HEMTs), based on III-nitrides wide bandgap semiconductors like AlGaN/GaN and AlInN/GaN, are extremely promising devices for high temperature, high power and high speed applications at microwave frequencies, owing to their properties of wide energy bandgap, high saturation electron drift velocity, large conduction band discontinuity and high thermal stability [1,2]. The lattice mismatch between the Al(Ga,In)N and GaN layers produces strong spontaneous and strain-induced piezoelectric polarization field that leads to a large conduction band bending at the heterojunction interface.…”

Normally-off p-GaN gate InAlN/GaN HEMTs grown on silicon substrates

“…The disadvantages are that the obtainable threshold voltages are relatively low and the gate leakage is larger. An AlGaN back-barrier can further improve these characteristics through increasing the threshold voltage by acting as a virtual p-type doping and mitigating the buffer leakage current by providing effective confinement of the electrons in the 2DEG region 17 .…”

The application of magnetic self-filter to optimization of AIN film growth process during the impulse plasma deposition synthesis

“…AlN is a dielectric material with a wide direct band gap of about 6 eV [1][2][3], which stands out among the oxides, carbides and nitrides with good thermal conductivity of about 285 W·m −1 ·K −1 [4]. A set of properties that represent this film material makes it appropriate for a wide range of applications in the technology of electronic materials [5][6][7][8][9][10]. Encouraging opportunities that entail the development of an efficient synthesis technology of AlN has led to numerous publications.…”