Silicon thin films were deposited by low-pressure chemical vapor deposition
(LPCVD) on oxidized silicon substrates, from silane decomposition. The dep
osition temperatures used in our experiment have been 500, 530, 550, 590 an
d 615 degreesC and the pressure values were 20, 53 and 100 Pa. The microstr
ucture and the surface roughness of as-deposited films were investigated by
X-ray diffraction (XRD), spectroelipsometry (using the Bruggemann-Effectiv
e Medium Approximation with a multilayer model) and AFM techniques. Three d
ifferent models, Tauc, Cody and Wemple-Di Domenico were used to estimate th
e values of the optical gap. The results show the influence of the microstr
ucture on the physical and optical properties of as-deposited LPCVD silicon
films. It is pointed out that polycrystalline silicon thin films can be ob
tained by the LPCVD technique below 550 degreesC. (C) 2001 Elsevier Science
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