Growth and properties of nanocrystalline germanium and germanium-carbide films and devices

Nanocrystalline Ge:H and (Ge,C):H are potentially important materials for photovoltaic energy conversion. In this paper, we report on the growth of these materials using remote ECR plasma deposition techniques. The materials were grown using a high degree of hydrogen to germane dilution. The as-grown materials had predominantly <220> orientation. Grain size was found to depend critically upon hydrogen dilution, with low hydrogen dilutions yielding larger grains. Hall measurements showed electron mobility to be as large as 6 cm/sup 2//V-sec. p-n junction devices were made in the material and showed photovoltaic effect. The quantum efficiency extended out to 0.8 eV. Addition of C to Ge reduced the crystallinity.