Band structure model of Ge-C alloy films prepared from tetraethylgermanium in A R.F. discharge

Investigations were carried out on the optical absorption and d.c. conductivity of plasma deposited hydrogenated amorphous Ge-C (a-GexCy:H) films from tetraethylgermanium at various values of r.f. power (P). It was found that two groups of these films exist: dielectric (prepared at P less-than-or-equal-to 20 W) and semiconducting material (P greater-than-or-equal-to 30 W). The electronic structure of the semiconducting films was investigated by external and internal photoemission studies. An energy level diagram is proposed to describe this structure.