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Relation between Microstructure and 2DEG Properties of AlGaN/GaN Structures
Author(s) -
Van Daele B.,
Van Tendeloo G.,
Germain M.,
Leys M.,
Bougrioua Z.,
Moerman I.
Publication year - 2002
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(200212)234:3<830::aid-pssb830>3.0.co;2-o
Subject(s) - materials science , microstructure , dislocation , transmission electron microscopy , optoelectronics , layer (electronics) , electric field , composite material , condensed matter physics , nanotechnology , physics , quantum mechanics
Several AlGaN layers are grown on top of a GaN buffer layer with the same Al concentration but different thickness. The electrical properties of these layers show a clear dependence on the AlGaN thickness. This electrical behaviour can be related to the microstructure, which is investigated by transmission electron microscopy. The formation of basal dislocations in the GaN and bending of the threading dislocations (in the samples with the thickest AlGaN/GaN cap layers) indicate a change of the stress in the GaN. This influences the piezo‐electric field and increases the carrier density. The AlGaN cap layer is able to filter threading dislocations. The filtering mechanism is a strain‐induced interaction with growth defects.