Stress splitting of the 0.84-eV luminescence in GaAs : Cr

Abstract

The photoluminescence spectra of Cr-doped GaAs at 4.2 K exhibits a narrow zero-phonon line (linewidth 1.1 meV) at 0.838 eV, accompanied by a broad phonon structure. The zero-phonon line is split by uniaxial stress. The splitting pattern and the line polarization are explained in terms of transitions to spin-orbit split states of the d shell of Cr2+. Transitions to bound-hole states and the existence of Cr as a complex can be excluded. The results are consistent with an internal transition between an excited state 5E of Cr2+ and the spin-orbit split state(s) 5T2 of Cr2+.