The epitaxial growth of germanium and silicon on an Ag(111) film on a mica substrate

With the aim of finding a method of obtaining self-supporting single-crystal films of silicon for solar cells we studied the epitaxial growth of silicon and germanium prepared by evaporation in ultrahigh vacuum onto an Ag(111) film evaporated in situ onto a mica substrate cleaved in air. The films were examined mainly by reflection high energy electron diffraction. Silicon and germanium films 50-200 Å thick were composed of crystallites with two main orientations relative to the substrate and unoriented crystallites in varying proportions depending on the substrate temperature T_s and the previous heat treatment temperature T_H of the mica. Nearly single-crystal films of silicon could be obtained for T_s = 350 °C and T_H = 250 °C. The sticking coefficient for silicon on silver was found to decrease almost to zero for T_s = 420 °C with T_H = 250 °C. No single-crystal films of germanium were obtained.