APPLICATION OF REAL-TIME SPECTROSCOPIC ELLIPSOMETRY FOR CHARACTERIZING THE STRUCTURE AND OPTICAL-PROPERTIES OF MICROCRYSTALLINE COMPONENT LAYERS OF AMORPHOUS-SEMICONDUCTOR SOLAR-CELLS

Over the past few years, we have applied real-time spectroscopic ellip sometry (RTSE) to probe hydrogenated amorphous silicon (a-Si:H)-based solar cell fabrication on the research scale. From RTSE measurements, the microstructural development of the component layers of the cell ca n be characterized with sub-monolayer sensitivity, including the time evolution of (i) the bulk layer thicknesses which provide the depositi on rates, and (ii) the surface roughness layer thicknesses which provi de insights into precursor surface diffusion. In the same analysis, RT SE also yields the optical properties of the growing films, including the dielectric functions and optical gaps. Results reported earlier ha ve been confined to p-i-n and n-i-p cells consisting solely of amorpho us layers, because such layers are found to grow homogeneously, making data analysis relatively straightforward. In this study, we report th e first results of an analysis of RTSE data collected during the depos ition of an n-type microcrystalline silicon (mu c-Si:H) component laye r in an a-Si:II p-i-n solar cell. Such an analysis is more difficult o wing to (i) the modification of the underlying i-layer by the H-2-rich plasma used in doped mu c-Si:H growth and (ii) the more complex morph ological development of mu c-Si:H, including surface roughening during growth.