Germanium films have been grown via the pyrolysis of mixtures on thin films of silicon grown on spinel and sapphire. The thin layer of silicon (≈1000Aå) was used to produce improved crystal structure in the germanium layer. In addition, the silicon undercoating provided improved adhesion of the germanium to the substrate, particularly at germanium growth temperatures above 700°C. The electrical properties of the films are described in terms of substrate orientation, silicon and germanium growth temperatures, and doping density. Both p‐ and n‐type films 2 µm thick have been grown reproducibly with mobilities in excess of 1200 cm2/V sec at carrier concentrations in the 1016/cm3–1017/cm3 range. These films were sufficiently perfect to allow observation of the indirect‐direct transition in the conduction band at 0.8 ev in the optical absorption data.