An anomalous increase in the fill factor of the current–voltage characteristic in the short wave region of the solar spectrum for a silicon photocell containing a porous silicon structure

Abstract

The possibility of increasing the efficiency of a silicon photocell by forming a porous silicon struc ture in its bulk has been proposed and studied. Photocells produced from p type single crystal silicon plates by the diffusion method were investigated. Porous silicon structures were formed by photoelectric anodic etching in HF–ethanol mixture. Current density and etching time were assigned by a computer in ranges of 6–14 mA/cm2 and 10–20 s, respectively. It has been found that the porous silicon structure located in the emitter bulk substantially improves efficiency of photocells. At wavelength λ ~ 550 nm, an anomalously large (by five to nine times) increase in efficiency was observed.