Evolution of structural properties and formation of NN split interstitials in GaAs_{1x} N_{x} alloys
Abstract
Using firstprinciples total energy calculations, we have studied the structural properties of the large lattice mismatched GaAs_{1x} N_{x} alloys. We first discuss the validity of Vegard’s law, which assumes a linear variation of the alloy concentration with both the lattice constant and the volume. In the diluteN limit, the calculated lattice constant coincides with Vegard’s law for the lattice constant, but not for the volume variation. This deviation implies that using Vegard’s law for the volume variation overestimates the N concentration. In the diluteAs limit, the calculated lattice constant is larger than that suggested by the Vegard’s law for both the volume and the lattice constant, implying that using Vegard’s law overestimates the As concentration. The calculated bulk moduli for GaAs_{1x} N_{x} , however, show almost linear behavior in the two region, increase monotonically with N concentration. We have also studied the effect of the split interstitial defect (NN)_{spl} , on the electronic and structural properties of the alloy. We find that the split interstitial is an amphoteric defect with (+/0) transition at 0.2 eV and (0/) transition at 0.3 eV above the valence band maximum. The concentration of the split nitrogen interstitial [NN] is relatively small compared to the substitutional nitrogen [N], but it would be large if the system could be grown at the Asrich limit and the sample were doped n type.
 Publication:

Physical Review B
 Pub Date:
 April 2005
 DOI:
 10.1103/PhysRevB.71.165212
 Bibcode:
 2005PhRvB..71p5212C
 Keywords:

 71.55.i;
 61.72.Vv;
 Impurity and defect levels;
 Doping and impurity implantation in IIIV and IIVI semiconductors