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Band Offsets In GaN/AlN and AlN/SiC Heterojunctions

Published online by Cambridge University Press:  10 February 2011

Nadia Binggeli ,
Philippe Ferrara  and
Alfonso Baldereschi
Nadia Binggeli
Affiliation:
Institut de Physique Appliquée, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
Philippe Ferrara
Affiliation:
Biochemisches Institut der Universität Zürich, CH-8057 Zürich, Switzerland
Alfonso Baldereschi
Affiliation:
Institut de Physique Appliquée, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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Abstract

We have investigated the structural trends of the band offsets in GaN/AlN and AlN/SiC heterojunctions using the ab initio pseudopotential method. In the zincblende GaN/AlN (100), (110), and (111) heterojunctions, the band offsets are relatively insensitive to interface orientation. Bulk strain effects, however, can modify the offset by as much as 0.4 eV in coherently strained AlN/GaN and GaN/AlN (100) junctions. The band alignment in the heterovalent AlN/SiC (110) and (111) heterojunctions depends on the geometry and stoichiometry of the interface. Valence band offsets as high as 2.5 eV are obtained for neutral AlN/SiC(11) junctions with a mixed Al/Si interface layer and as low as 1.3 eV with a mixed N/C layer. Atomic relaxation plays a major role in determining the offset. The change from zincblende (111) to wurtzite (0001) crystal structure in GaN/AlN and AlN/SiC heterojunctions selectively affects the conduction band offset, and has only a minor influence on the valence discontinuity.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 482 , 1997 , 911
Copyright
Copyright © Materials Research Society 1998

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