The real band diagram for the metal-semiconductor heterojunction

For NbN-GaAs heterostructures the transverse photovoltage spectral curves were studied. The photovoltage taken for the samples annealed at T=850/spl deg/C changed its polarity near the GaAs intrinsic absorption edge. A complicated form of the observed spectral curves is related to the interaction between the photocurrents generated by illumination in both the GaAs bulk and space charge region near the NbN film. Heat annealing at T=950/spl deg/C makes the near-surface band bending uniform; the photovoltage holds its polarity in the spectral range studied. Basing on the analysis of the spectral curves features, we have built a real band diagram for the NbN-GaAs heterojunction.