Optical Energy Gap of Magnetically Confined Arc Discharge D.C. Sputtered Hydrogenated Amorphous Silicon

Abstract

The optical energy gap of undoped hydrogenated amorphous silicon (a-Si:H) films prepared by using a magnetically confined arc discharge d.c. sputtering system has been investigated. The detail of the sputtering system used here is presented. High purity silicon polycrystalline target has been used. This work discussed experimental evidence that at different hydrogen partial pressures, during sputtering, and substrate temperature will have quite different values for the optical gap. This, results from the different values and distribution of the density of states in the mobility gap of the material. In this technique, it was found that the optimum hydrogen pressure and substrate temperature for good stability, high optical energy gap and singly hydride samples, obtained from the analysis of infrared transmission spectrum, were deposited at 8 x 10" 4 mbar and 523 K respectively. This hydrogenated amorphous silicon is useful for photovoltaic technology (i.e. solar electricity...).