The optical properties of Amorphous Semiconductors. Part-I: Amorphous Materials

The optical properties of amorphous semiconductors have been discussed. Since the principles of interpreting the results for most amorphous non-metallic materials are broadly the same, the oxide glasses and amorphous thin films have been included in the discussion.The basic properties of crystalline and non-crystalline non-metallic materials have been discussed. The physical and structural differences between crystalline and amorphous materials have been described. It has been shown that the wave vector k is not effectively a good quantum number in amorphous non-crystalline materials and such materials are usually regarded as indirect gap materials. So the indirect gap materials are not suitable for making light emitting semiconductor diodes. The mobility gap is greater than the energy gap of the same material in crystalline form. (author). 14 refs., 4 figs