LAUSR

Abstract We studied the effects of precursor gas composition and the addition of dopant gas, PH3, on polycrystalline silicon films deposited using plasma-enhanced chemical vapor deposition. Spectroscopic ellipsometry measurement and modeling results revealed that the poly-Si films consist of a subsurface layer and a bulk layer. The sample deposited under greater hydrogen dilution exhibited a fully crystallized subsurface layer and a denser bulk layer. We also studied the effects of various dopant gas flow rates on structural and electrical properties of the poly-Si films. Ellipsometry, X-ray diffraction, and Raman analyses revealed that the film deposited using a large dopant-gas flow rate exhibits decreased grain size and increased void fraction. Furthermore, the doped poly-Si films show a trend of Raman peak shift, which was attributed to tensile stress. The stress of the doped poly-Si films increases with higher dopant-gas flow rate. Measurement of the temperature-dependent dark conductivity shows saturation of the electrical conductivity of heavily doped films.