Impediment of the majority carrier current by grain boundary potential in Al-poly-Si Schottky barrier solar cells

A theoretical analysis is made to explain the non-exponential current-voltage characteristics observed in Al-Poly-Si (Wacker) Schottky-barrier solar cells fabricated in our laboratory. In this model, we consider an effective grain boundary in parallel with the Schottky junction. Comparison between experimental data and numerical calculation indicates that the grain boundary may be represented by a fixed interface charge, a uniformly distributed interface state density and a neutral level Eo. Diodes fabricated in regions with high-angle grain boundaries behave in a manner which conforms closely with the proposed model.