Relationship Between Structural and Optical Properties in Polycrystalline Silicon Films Prepared at Low Temperature by Plasma‐Enhanced Chemical Vapor Deposition

Abstract

Polycrystalline silicon (poly‐Si) films were deposited by plasma‐enhanced chemical vapor deposition with a mixture of silane and silicon tetrafluoride diluted with hydrogen, and their structural, optical, and bonding properties were investigated. Poly‐Si films with a crystalline volume fraction of 80% at a substrate temperature no more than 300°C can be deposited, and lowering the substrate temperature resulted in decreased crystalline grain size. Also, a decrease in the size from microcrystalline to nanocrystalline grains can be achieved by increasing the hydrogen dilution ratio to the mixture. On the other hand, the increase in the hydrogen causes an increase in the crystalline volume fraction which was estimated from Raman scattering spectra. The structural properties for the surface of crystallites in the poly‐Si films were investigated by means of X‐ray diffraction and Fourier transform infrared spectroscopy. Furthermore, the photoluminescent response measured for the poly‐Si films was investigated in connection with the structural properties.