ORIGIN OF SHARP NEAR-INFRARED TRANSITIONS IN CHROMIUM DOPED III-V SEMICONDUCTORS

It is contended that the sharp emission and absorption lines seen in GaAs:Cr and GaP:Cr at 0.839 eV and 1.029 eV are due to a type of excitonic recombination at isoelectronic sites involving chromium. This assignment contrasts strongly with the widely accepted model involving an internal d-d transition at isolated Cr2+ centres. The new description satisfactorily accounts for many puzzling features relating to the high transition energies, phonon coupling, Stokes shifts, stress splittings, non-correlation of optical and EPR data and the large multiplicity of fine structure seen in high resolution optical spectroscopy. © 1979.