In one embodiment, a method for epitaxially forming a silicon-containing material on a substrate surface is provided which includes positioning a substrate having a monocrystalline surface and a second surface (amorphous or polycrystalline) into a process chamber and exposing the substrate to a deposition gas to form an epitaxial layer on the monocrystalline surface and a polycrystalline layer onthe second surface. The deposition gas preferably contains a silicon source and at least a second elemental source, such as a germanium source, a carbon source or both. Thereafter, the method furtherprovides exposing the substrate to an etchant gas such that the polycrystalline layer is etched at a faster rate than the epitaxial layer. The substrate may be sequentially and repetitively exposed to the deposition and etchant gases to form the silicon-containing material. In one example, the deposition gas contains silane and etchant gas contains chlorine and nitrogen.