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Strain relaxation in AlN/GaN heterostructures grown by molecular beam epitaxy
Author(s) -
Dimitrakopulos G. P.,
Komninou Ph.,
Kehagias Th.,
Sahonta S.L.,
Kioseoglou J.,
Vouroutzis N.,
Hausler I.,
Neumann W.,
Iliopoulos E.,
Georgakilas A.,
Karakostas Th.
Publication year - 2008
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200780137
Subject(s) - heterojunction , materials science , molecular beam epitaxy , transmission electron microscopy , strain (injury) , relaxation (psychology) , optoelectronics , layer (electronics) , stress relaxation , epitaxy , composite material , nanotechnology , medicine , psychology , social psychology , creep
The strain distribution and defects in a graded AlN/GaN heterostructure comprising AlN layers from 3 nm up to 100 nm grown by plasma‐assisted MBE were studied using transmission electron microscopy techniques. Gradual strain relaxation was observed as well as strain partitioning between the GaN spacers and the thicker AlN layers. Elastic strain is retained even in the thicker layers of the heterostructure. Extensive introduction of threading and misfit dislocations is observed at and above the 7 nm AlN layer. The threading dislocations adopt inclined zig‐zag line directions thus contributing to the relief of alternating compressive‐tensile elastic strain across the the layers of the heterostructure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)