The deposition of Si1−xGexalloy layers in an atmospheric‐pressure, chemical vapor deposition reactor has been studied by separately examining the silicon and the germanium components of the deposition rate. The overall deposition rate increases approximately linearly with GeH4partial pressure, but is relatively independent of SiH2Cl2partial pressure. The silicon component of the deposition rate increases rapidly with increasing temperature for a constant germanium content, but the germanium component changes only slowly above about 675 °C, and is probably limited by mass transport.