Piezospectroscopy of vanadium-doped indium phosphide

The authors have studied the 705.45 meV photoluminescence (PL) zero-phonon line (ZPL) of vanadium-doped InP and the 993 meV ZPL observed in the excitation spectrum of the 705 meV PL band. The behaviour of these lines under uniaxial stress indicates a tetragonal distortion in the initial state of the PL and a trigonal distortion in the final state of the excitation transition. These different symmetries suggest very strongly that the distortions arise from Jahn-Teller coupling. They are consistent with the assignments of Skolnick and co-workers (1983) to crystal-field transitions of V In 3+ (d 2 ). Evidence that the same assignments apply to the similar PL bands of GaAs:V and GaP:V is provided by the structure of their ZPLs. The phonon coupling of crystal-field levels of Co 2+ and V 3+ in III-V semiconductors is compared. It is suggested that in all these systems the T 2 (F) levels are weakly coupled to epsilon modes, and the T 1 (F) levels are strongly coupled to tau 2 modes.