Physical properties of polycrystalline silicon films related to LPCVD conditions

The properties of polycrystalline silicon films have been investigated in r elation to low pressure chemically vapour deposited (LPCVD) conditions, suc h as gas chemical content, pressure and temperature in the range of 500-615 degreesC. A careful investigation of the 250-400-nm reflection spectra ind icates a definite dependence on the temperature and growth rate for LPCVD p oly-Si films. The disorder in as-deposited samples produces changes to the main peaks of optical transition in c-Si described by the complex band theo ry. The percentage of the disorder has been associated with changes in Gamm a'(23)-Gamma (15) at 365-nm and in X-4-X-1 at 280-nm optical transitions ob tained by a deconvolution approach to UV spectra. The most disordered LPCVD poly-Si samples have been obtained at 550 degreesC for a deposition pressu re of 400 mtorr. Optical properties are discussed in relation to CVD condit ions and are related to XRD data. (C) 2001 Elsevier Science B.V. All rights reserved.