Optical constants of amorphous hydrogenated germanium thin films

The optical constants (n + ik) and dielectric function (in(1) + iin(2)) of thin films of amorphous hydrogenated germanium prepared by glow discharge decomposition of germane have been determined by photometry. The results were shown to be essentially unaffected by the presence of an oxide overlayer in contrast to recent results obtained using ellipsometry. The effect of deposition temperature was investigated. The effect of increasing substrate temperature is to increase the height of the peak in in(2) and the energy at which the peak occurs. The energy gap E(0) is not significantly affected by substrate temperature and has the value of 1.06 eV.