Determination of Interface and Surface Structure During the Growth of a-Si:H-Based Heterostructures

Abstract

AbstractEllipsometry measurements of hydrogenated amorphous silicon (a-Si:H)-based heterostructures have been used to characterize surfaces and single interfaces. From spectroscopic studies before and after plasma oxidation of a-Si:H, surface roughness on the atomic scal; (in the plane of the surface) can be distinguished from larger scale (> 100 Å) modulation. We also show how in situ studies of heterostructure preparation can be used to set deposition conditions to minimize near-interface layers owing to thickness dependent film properties. When these are eliminated, the discrepancies in the data from planar layer-bylayer growth models can be attributed to the larger scale surface and interface modulation. Finally, extensive deviations from planar growth for a-Si:H/μc-Si:H have been characterized in terms of specific heterogeneities.