Specific Features of the Photoconductivity of Compensated i -GaAs in the Spectral Range with h ν > E g

Abstract

The photoconductivity of semi-insulating GaAs compensated by chromium oxide is investigated. It is demonstrated that after heat treatment, the current photosensitivity of a sample irradiated with particles whose energies exceed the band gap reaches large values, which does not agree with the De Vore theory. These large photosensitivity values are due to slowing down of the surface recombination caused by the presence of oxygen in i-GaAs. The high current photosensitivity extends to λ = 0.52 μm. The observed structure of the photoconductivity spectrum is most likely caused by vertical electron transitions from the valence subband, split in the process of spin-orbital interaction, to the central minimum of the conduction band. The influence of crystal irradiation by particles with energies hν > Eg on the spectral photoconductivity distribution is investigated. It is demonstrated that irradiation by electrons and γ-quanta causes the photocurrent to increase. After neutron irradiation, the photocurrent decreases at short wavelengths in accordance with the De Vore theory. It is demonstrated that i-GaAs is a very sensitive detector of red radiation.