Magnetophotoconductivity Due to Intra-Shallow-Donor Transitions in Semi-Insulating GaAs

The paper concerns investigations of shallow centres in semi-insulating (SI) GaAs samples. A very sensitive measuring method - magnetophotoconductivity due to intra-shallow-donor transitions - was used. We report the behaviour of intra-impurity transitions as well as an additional structure in low magnetic fields for different far-infrared wavelengths (70.6 μm, 96.5 μm, 118.8 μm, 163 µm). The results are discussed in terms of a fluctuating potential from ionized centres in SI GaAs. The physical mechanism responsible for the low magnetic field structure is proposed.