General properties of SnO2-GaAs and SnO2-Ge heterojunction photovoltaic cells

Abstract

SnO 2 -Ge and SnO 2 -GaAs heterojunction formed by chemical vapor deposition have been investigated. The results show that (n-n) SnO 2 -GaAs, (n-p) SnO 2 -GaAs, and (n-n) SnO 2 -Ge heterojunctions give a photovoltaic effect, while (n-p) SnO 2 -Ge yields an ohmic contact. The measured short-circuit currents, arising mainly from semiconductor side, are comparable with those for AMOS and homojunction solar cells. The open-circuit voltage and fill factor and considerably less. The polarity observed in V oc and I sc is consistent with the band bending of a simple SnO 2 -semiconductor heterojunction energy-band diagram neglecting interface states. The ohmic behavior for (n-p) SnO 2 -Ge is attributed to the accumulation layer existing between SnO 2 conduction band and Ge valence band at the interface.