ROUGHNESS EFFECT AN HETEROJUNCTION PHOTOVOLTAICS

In this work, we present an investigation of the junction interface ro ughness effect on the open circuit voltage, V-oc for thin film heteroj unction photovoltaics. The roughness effect is studied for self-affine rough interfaces, which are described in Fourier space by the correla tion model similar to sigma(2) xi(2)(1 + aq(2) xi(2))(-1-H). sigma, xi , and H denote, respectively, the rms roughness, the in-plane roughnes s correlation length, and the interface irregularity exponent (0<H<1). The roughness effect becomes significant for small H (<0.5), and for large long-wavelength roughness of typical values sigma/xi similar to 0.1. The junction interface roughness may yield a contribution to V-oc even up to 10%. Comparison of the results is performed with predictio ns in real heterojunctions, e.g., CuxS/(Zn)CdS. (C) 1996 American Inst itute of Physics.