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The scaling behaviour of surface roughness evolution of microcrystalline silicon (μc-Si:H) films prepared by veryhigh frequency plasma-enhanced chemical vapour deposition (VHF-PECVD) has been investigated by using a spectroscopic ellipsometry (SE) technique. The growth exponent β was analysed for the films deposited under different pressures Pg . The results suggest that films deposited at Pg = 70 Pa have a growth exponent β about 0.22, which corresponds to the definite diffusion growth. However, abnormal scaling behaviour occurs in the films deposited at Pg = 300 Pa. The exponent β is about 0.81 that is much larger than 0.5 of zero diffusion limit in the scaling theory. The growth mode of μc-Si:H deposited at Pg = 300 Pa is clearly different from that of μc-Si:H at Pg = 70 Pa. Monte Carlo simulations indicate that the sticking process and the surface diffusion of the radicals are two key factors to affect the growth mode under different pressures. Under Pg = 300 Pa, β>0.5 is correlated with the strong shadowing effect resulting from the larger sticking coefficient.
The scaling behavior of surface roughness evolution of microcrystalline silicon (μc-Si: H) films prepared by very high frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) has been investigated by using a spectroscopic ellipsometry (SE) technique. The results suggest that the films deposited at Pg = 70 Pa have a growth exponent β of about 0.22, which corresponds to the definite diffusion growth. However, abnormal scaling behavior occurs in the films deposited at Pg = 300 Pa. The exponent β is about 0.81 that is much larger than 0.5 of zero diffusion limit in the scaling theory. The growth mode of μc-Si: H deposited at Pg = 300 Pa is clearly different from that of μc-Si: H at Pg = 70 Pa. Monte Carlo simulations indicate that the sticking process and the surface diffusion of the radicals are two key factors to affect the growth mode under different pressures. Under Pg = 300 Pa, β> 0.5 is co rrelated with the strong shadowing effect resulting from the larger sticking coefficient.