Evidence for a phosphorus-related interfacial defect complex at a GaP/GaNP heterojunction

Optically detected magnetic resonance (ODMR) studies of molecular beam epitaxial GaNP/GaP structures reveal presence of a P-related complex defect, evident from its resolved hyperfine interaction between an unpaired electronic spin (S=1/2) and a nuclear spin (I=1/2) of a P-31 atom. The principal axis of the defect is concluded to be along a < 111 > crystallographic direction from angular dependence of the ODMR spectrum, restricting the P atom (either a P-Ga antisite or a P-i interstitial) and its partner in the complex defect to be oriented along this direction. The principal values of the electronic g tensor and hyperfine interaction tensor are determined as: g(perpendicular to) = 2.013, g(parallel to) = 2.002, and A(perpendicular to) = 130 x 10(-4) cm(-1), A(parallel to) = 330 x 10(-4) cm(-1), respectively. The interface nature of the defect is clearly manifested by the absence of the ODMR lines originating from two out of four equivalent < 111 > orientations. Defect formation is shown to be facilitated by nitrogen ion bombardment under nonequilibrium growth conditions and the defect is thermally stable upon post-growth thermal annealing.