The deposition of undoped polycrystalline silicon‐germanium alloy films onto by the pyrolysis of and in a low‐pressure chemical vapor deposition system is described. The deposited films are compatible with standard wet‐cleaning baths, and their formation and patterning are very controllable processes; therefore, their application should not introduce significant process complexity into silicon‐based technologies. Depending upon their Ge content, films can be deposited in polycrystalline form at temperatures as low as ∼400°C, because the transition temperature between polycrystalline and amorphous film deposition decreases with increasing Ge content. grains are columnar in structure and have a relatively low density of microtwins, and their average size is larger than that of grains in poly‐Si films deposited at the same temperature. These properties of make it a promising material for thin film transistor applications in three‐dimensionally integrated circuits and large‐area electronics technologies, which have limited thermal process budget requirements.