We have studied the structural evolution in amorphous and microcrystalline silicon deposited from silane-argon mixture by radio frequency plasma enhanced chemical vapour deposition (PECVD) method.Sharp increase in small angle x-ray scattering (SAXS) intensity,in accordance with tilt measurements,indicates columnar morphology in the sample deposited in the amorphous-microcrystalline transition region.The variation of SAXS measured heterogeneity and a gradual shift of Si-H stretching vibrational frequency at 2000 cm~(-1) towards higher wave number with increase of power density indicate structural modifications in the films.Observation of sharp increase in the ratio of the intensity of Ar to SiH in the transition region may explain the surface modification assisted by Ar and hence the structural changes in the material.
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