Stabilization of amorphous GaN by oxygen
cond-mat.mtrl-sci
/ Authors
F. Budde, B. J. Ruck, A. Koo, S. Granville, H. J. Trodahl, A. Bittar, G. V. M. Williams, M. J. Ariza, B. Bonnet, D. J. Jones
and 3 more authors
/ Abstract
Ion assisted deposition (IAD) has been investigated for the growth of GaN, and the resulting films studied by x-ray diffraction and absorption spectroscopy and by transmission electron microscopy. IAD grown stoichiometric GaN consists of random-stacked quasicrystals of some 3 nm diameter. Amorphous material is formed only by incorporation of 15% or more oxygen, which we attribute to the presence of non-tetrahedral bonds centered on oxygen. The ionic favourability of heteropolar bonds and its strikingly simple constraint to even-membered rings is the likely cause of the instability of stoichiometric a-GaN.