Evidence of Γ-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-like diamond anvil cell.The observation that the energy position of the line follows that of the Γ-conduction band minimum in the 1 bar-30 kbar pressure range demonstrates that the line has Γ-(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.