Selective epitaxy of GexSi1−xin an ultrahigh‐vacuum chemical vapor deposition reactor from SiH4and GeH4/H2is reported for the first time. Growth is performed at 600 °C on patterned wafers after an 800 °C bake which provides a clean silicon surface. Selective growth is maintained during a short incubation time. GeH4/H2is found to increase the incubation time and the growth rate improving selectivity. Diodes fabricated from selectively grown films demonstrate high material and film/oxide interface quality.