DEPOSITION AND PROPERTIES OF GERMANIUM-CARBON ALLOY-FILMS PRODUCED FROM TETRAETHYLGERMANIUM IN AN RF DISCHARGE

Thin films of a relatively low concentration of germanium exhibiting electrical conductivities up to 7 × 10-5 (ω cm)-1 were prepared by r.f. glow discharge decomposition of tetraethylgermanium in a stream of argon. Physical properties such as density, refractive index and electrical conductivity were determined over the range of r.f. power from 10 to 100 W. Power loads under 30 W yielded soft and transparent polymeric materials of low conductivities and low densities while films obtained at higher power loads were glassy in appearance, non-transparent, black, hard and dense (densities in the range 3.0-3.6 g cm-3). The conditions yielding optimum values of important physical parameters were established for depositions on the lower excited electrode. For a monomer flow rate of 0.44 standard cm3 min-1 and an argon flow rate of 20 standard cm3 min-1 the highest values of the electrical conductivity, density and refractive index were obtained at a power load of 50 W. In terms of energy input per unit mass of monomer, this corresponds to about 0.8 × 109 J kg-1. The Auger spectroscopic measurements showed that the highest content of germanium was found in the films deposited on the lower electrode under these conditions. Pattern generation by means of photolithography and subsequent reactive ion etching was carried out with a lateral resolution of approximately 1 μm. © 1990.