Characterization of heat-treated ITO/InP solar cells

The effects of heat treatments on the properties of InP/ITO junctions were studied using time resolved photoluminescence measurements, surface chemical analysis, and photo $I–V$ characteristics. It was found that the surface recombination velocity (SRV) of etched InP increased from 600 to $∼4×104 cm/s$ after a 350 °C heat treatment and to about $4×105 cm/s$following annealing at 500 °C. On the other hand annealings performed on Ar plasma treated samples increased the substrate’s SRV to similar values following 80 and 200 °C heat treatments, respectively. Surface chemical analysis showed that the increase in SRV is associated with phosphorus loss from the crystal surface which creates recombination centers at the interface. The effect of these recombination centers on the open circuit voltage of ITO/InP solar cells is demonstrated and discussed.