OPTICAL DEPTH PROFILING OF BAND-GAP ENGINEERED INTERFACES IN AMORPHOUS-SILICON SOLAR-CELLS AT MONOLAYER RESOLUTION

Real time spectroellipsometry and a two-layer optical analysis have be en applied to obtain alloy composition (x) and optical gap (E-g) depth profiles with similar to 3 Angstrom resolution and sensitivities bett er than +/-0.01 in x and +/-0.02 eV in E-g for graded amorphous semico nductor alloy thin films prepared by plasma-enhanced chemical vapor de position. Graded amorphous silicon-carbon alloy (a-Si1-xCx:H) layers i ncorporated at the i-p interfaces of a-Si:H n-i-p solar cells have bee n studied using these methods, and the layer characteristics have been related to improvements in solar cell performance. (C) 1998 American Institute of Physics.