EVIDENCE OF GAMMA-FREE OR BOUND-TO-DEEP ACCEPTOR CHARACTER OF THE Y-1.2 EV DEEP PHOTOLUMINESCENCE LINE IN N-TYPE GE-DOPED GAAS DERIVED FROM HIGH HYDROSTATIC-PRESSURE EXPERIMENTS IN DIAMOND-ANVIL CELL

The dependence of the energy position of the deep defect-related photoluminescence line Y-1.2 eV in Ge-doped GaAs on high hydrostatic pressure is investigated using a Dunstan-type diamond anvil cell. The observation that the energy position of the line follows that of the GAMMA-conduction band minimum in the 1 bar-30 kbar pressure range demonstrates that the line has GAMMA-(free or shallow bound)-to-deep acceptor character. This fact confirms the deep-acceptor character of the deep defect, most likely a donor impurity-Ga vacancy complex, which contributes to the Y-1.2 eV photoluminescence line.