Photocapacitance measurements of the two acceptor levels of chromium in GaAs

Abstract

The photoionisation spectra for transitions to the conduction band from the two acceptor levels in GaAs:Cr have been measured by a photocapacitance method. At liquid nitrogen temperature, the transition from the first level to the conduction band has a threshold at 0.74+or-0.01 eV. The threshold for transitions from the valence band to this level has been observed at 0.81+or-0.01 eV. There is no clear threshold for transitions from the second level to the conduction band because of phonon interactions, but the level lies about 0.5 eV below the band. The published spectra of photoexcited ESR in GaAs:Cr and GaP:Cr are discussed in the light of the authors' results.