K. J. Nash

Optical studies of GaAs:Ti

In LEC-grown n-GaAs:Ti, a triple-peaked absorption band at 0.66 eV and a band at 1.01 eV are observed and interpreted as the 3A2 to 3T1(F) and to 3T1(P) transitions of TiGa2+. Sharp zero-phonon lines are seen in absorption at 0.566 and 0.569 eV, the former line also being observed as the zero-phonon component of a photoluminescence band. The absence of any Zeeman splitting of the lines up to fields of 10 T indicates that these lines do not arise from TiGa2+.

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 VIn3+ (d2). 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 Co2+ and V3+ in III-V semiconductors is compared. It is suggested that in all these systems the T2(F) levels are weakly coupled to epsilon modes, and the T1(F) levels are strongly coupled to tau 2 modes.

Many body resonant polaron interaction in quantum wells containing high densities of free carriers

Strong resonant polaron coupling phenomena in the photoluminescence spectra of modulation doped quantum wells are reported. The polaron interaction arises between hole quasi-particles in otherwise filled electron Landau levels, and LO phonons of the quantum well material.