Thin three-layered a-Si:H photoconductive structures have been studied for application in high resolution electrophotography. The resolution of prints is determined by the a-Si:C:H top layer. It is observed that the resolution of prints decreases from 100 to 30 lines/mm after about 25 charge cycles of corona discharge. The effect of corona charging on the surface properties of a-Si:C:H films with different carbon content is studied. Before and after corona exposure Fourier transform infrared absorption and lateral dark conductivity were measured. We observe that modes around 3300 cm-1, ascribed to H2O and -OH related modes, arise in combination with an increase of the lateral dark conductivity. This effect is not dependent on the film thickness, indicating that only the surface is affected by the corona discharge. The increase of the dark conductivity is interpreted as due to band bending at the surface, induced by the adsorption of H2O or the growth of a thin Si-OH layer at the surface.