Influence of film thickness on optical and electrical properties of hydrogenated amorphous silicon

The optical and electrical properties of hydrogenated amorphous silicon (a-Si:H) films produced by magnetron sputtering (SP) and glow discharge (GD) were studied as a function of the film thickness (50–300 nm). A strong dependence on the thickness was observed in the maximum values of the absorption coefficient and in the energy gap Eg (obtained from for both series. For the SP films the refractive index n(λ) increased with thickness, whereas for GD films ε2max and its corresponding energy decreased with increasing thickness. The resistivity values are within the range of typical values for a-Si:H, but no effect of thickness was observed, because of non-uniformity of the films and band bending at the substrate interface