OPTICAL-SPECTRA OF GLOW-DISCHARGE-DEPOSITED SILICON

The reflectance and the imaginary part ε2 of the dielectric function of glow- discharge-deposited silicon (g-Si) have been investigated in the energy range between 1 and 10 eV. The spectra depend strongly on the deposition temperature but do not change much after annealing. The ε2 peak, which is considerably larger in g-Si than in evaporated films, occurs also at higher energy, namely 3·55 eV. We assume that this results from an improvement of the covalent network by the incorporation of hydrogen. Decreasing deposition temperature reduces the oscillator strength of the optical transitions, particularly at high energy and this is interpreted as due to an increasing localization of the deeper-lying valence states. © 1979 Taylor & Francis Ltd.