The magnetic field dependence of the PEM effect in melt-grown InSb thin layers

The room temperature dependence of the PEM effect on magnetic field has been measured in intrinsic, melt-regrown layers of InSb of thickness from 1 to 10 μm. When illuminated on the surface of higher recombination velocity (the back surface of the InSb layer) the samples showed an anomalous magnetic field dependence of the PEM effect. This was manifested in most of the samples as a sign reversal in the PEM voltage, from a negative voltage in weak magnetic fields to a positive voltage in strong fields. Since, theoretically, such a PEM voltage dependence might result from a strong dependence of the bipolar diffusion length L on the magnetic field H, several scattering mechanisms have been investigated to find the strongest dependence of L = L(H) in InSb layers. It has been found that the dependence L = L(H) could in no case be responsible for the experimental magnetic field dependence of the PEM effect. Good agreement between theory and experiment is reached if a magnetic field-dependent surface recombination velocity at the InSb-substrate interface is postulated. The shape of the dependence which gave the best fitting of theoretical to experimental results is given.