Fine crystalline silicon grown at low temperatures : investigations by high resolution microscopy

The transition from amorphous to fine-crystalline silicon films deposited by plasma-enhanced chemical vapour deposition from SiH4/H-2 plasmas of different compositions was investigated by scanning tunneling microscopy (STM), atomic force microscopy (AFM) and Raman spectroscopy. We point out the usefulness of UHV scanning probe microscopy for studies on these films. This is in particular demonstrated for a mixed-phase film by a comparison to cross-sectional transmission electron microscopy. The film as prepared under present conditions exhibits a conical growth of crystallites nucleating close to the film-substrate interface and being surrounded by amorphous material. For this type of film the lateral distribution of nuclei can be studied by AFM and STM due to an extraordinarily low nucleation density