Premium
Ordering in undoped hexagonal Al x Ga 1– x N grown on sapphire (0001) with 0.09 < x < 0.247
Author(s) -
Laügt M.,
BelletAmalric E.,
Ruterana P.,
Omnès F.
Publication year - 2003
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/pssb.200301760
Subject(s) - metalorganic vapour phase epitaxy , sapphire , diffraction , alloy , transmission electron microscopy , epitaxy , crystallography , materials science , electron diffraction , lattice (music) , hexagonal crystal system , phase (matter) , x ray crystallography , analytical chemistry (journal) , condensed matter physics , chemistry , physics , optics , nanotechnology , layer (electronics) , laser , metallurgy , chromatography , organic chemistry , acoustics
Multiple ordering has been observed both by high resolution X‐ray diffraction (HRXRD) and transmission electron microscopy (TEM) in Al x Ga 1– x N grown by low pressure metal‐organic vapor phase epitaxy (LP‐MOVPE) on sapphire (0001) with x varying from 9 to 25 percent. This is shown to take place even simultaneously in the same sample; beside the disordered alloy, AlGaN 2 (1:1), and Al 0.25 Ga 0.75 N (3:1), there is an additional type which a quite large unit cell. In the latter, the c parameter is six times larger than that of the disordered alloy. Through the analysis of X‐ray diffraction data and comparison with TEM observations, a structure model is proposed. Taking into account the super‐lattice reflections intensity and symmetry, we conclude that this ordered phase contains two consecutive AlN monolayers in the 3.1 nm unit cell that corresponds to Al 0.16 Ga 0.84 N (10:2).