On Operation of PECVD of Thin Film Solar Cells∗

This work proposes a multiscale model-based operation framework for large-area plasma-enhanced chemical vapor deposition (PECVD) of thin film silicon solar cells with uniform thickness and film surface microstructure that optimizes light trapping. The results of a multiscale process model indicate that in order to manufacture a thin film with a diameter of 20 cm and a uniform thickness with surface microstructure that optimizes light trapping: a) a sinusoidally-grated wafer surface should be used in which the grating period and depth should correspond to values that lead to film surface roughness on the order of visible light wavelength range, and b) the substrate temperature should be regulated, along several concentric zones across the substrate, to compensate for a radially non-uniform deposition rate of the film on the wafer owing to gas-phase transport phenomena. Due to the dependence of film growth rate on substrate temperature, the wafer surface is separated into four concentric zones, each with an independent heating element. Simulations demonstrate that the use of appropriate sinusoidal wafer grating and the regulation of substrate temperature provide a viable and effective way for the large-area PECVD of thin film silicon solar cells with uniform thickness and film surface microstructure that optimizes light trapping.