Journal ArticleDOI
Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N- and Ga-face AlGaN/GaN heterostructures
Oliver Ambacher,Joseph A. Smart,James R. Shealy,Nils Weimann,K. Chu,M. J. Murphy,William J. Schaff,L.F. Eastman,Roman Dimitrov,L. Wittmer,Martin Stutzmann,W. Rieger,J. Hilsenbeck +12 more
TLDR
In this article, the authors investigated the role of spontaneous and piezoelectric polarization on the carrier confinement at GaN/AlGaN and AlGaN/GaN interfaces.Abstract:
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 ...read more
Citations
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Journal ArticleDOI
Band parameters for III–V compound semiconductors and their alloys
TL;DR: In this article, the authors present a comprehensive, up-to-date compilation of band parameters for the technologically important III-V zinc blende and wurtzite compound semiconductors.
Journal ArticleDOI
AlGaN/GaN HEMTs-an overview of device operation and applications
TL;DR: 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 of the AlGaN/GaN high-electron mobility transistor.
Journal ArticleDOI
Alternative Plasmonic Materials: Beyond Gold and Silver
TL;DR: This review explores different material classes for plasmonic and metamaterial applications, such as conventional semiconductors, transparent conducting oxides, perovskiteOxides, metal nitrides, silicides, germanides, and 2D materials such as graphene.
Journal ArticleDOI
Two dimensional electron gases induced by spontaneous and piezoelectric polarization in undoped and doped AlGaN/GaN heterostructures
Oliver Ambacher,B. E. Foutz,Joseph A. Smart,James R. Shealy,Nils Weimann,K. Chu,M. J. Murphy,A. J. Sierakowski,William J. Schaff,L.F. Eastman,Roman Dimitrov,A. Mitchell,Martin Stutzmann +12 more
TL;DR: In this paper, a combination of high resolution x-ray diffraction, atomic force microscopy, Hall effect, and capacitance-voltage profiling measurements is used to calculate the polarization induced sheet charge bound at the AlGaN/GaN interfaces.
Journal ArticleDOI
The impact of surface states on the DC and RF characteristics of AlGaN/GaN HFETs
TL;DR: In this article, the authors show that the cause of current collapse is a charging up of a second virtual gate, physically located in the gate drain access region, thus acting as a negatively charged virtual gate.
References
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Spontaneous polarization and piezoelectric constants of III-V nitrides
TL;DR: In this paper, the spontaneous polarization, dynamical Born charges, and piezoelectric constants of the III-V nitrides AlN, GaN, and InN are studied ab initio using the Berry-phase approach to polarization in solids.
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Electron mobilities in modulation‐doped semiconductor heterojunction superlattices
TL;DR: In this paper, a modulation-doping technique was used to spatially separate conduction electrons and their parent impurity atoms, thereby reducing the influence of ionized and neutral impurity scattering on the electron motion.
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Elastic properties of zinc-blende and wurtzite AlN, GaN, and InN
TL;DR: In this article, the elastic constants for zinc-blende and wurtzite were obtained from density-functional-theory calculations utilizing ab initio pseudopotentials and plane-wave expansions.
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Giant LO-TO splittings in perovskite ferroelectrics
TL;DR: Anomalously large dynamical effective charges give rise to very strong mixing of the mode eigenvectors on going from the TO to the LO case, resulting in a ``giant LO-TO splitting'' in the sense that the soft TO mode is most closely related to the hardest LO modes.
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Valence‐band discontinuities of wurtzite GaN, AlN, and InN heterojunctions measured by x‐ray photoemission spectroscopy
TL;DR: In this paper, the valence band discontinuities at various wurtzite GaN, AlN, and InN heterojunctions were measured by means of x-ray photoemission spectroscopy.