Fabrication and characterization of indium tin oxide (ITO)/polycrystalline silicon solar cells

Efficient indium tin oxide (ITO)/polycrystalline silicon heterojunction solar cells have been fabricated utilizing neutralized ion-beam sputtering techniques. These cells were fabricated on single-pass float-zone-refined silicon. Conversion efficiencies of 6.25% under AM1 illumination have been observed. Cells were analyzed by I-V characteristics and a scanning laser photoresponse technique. Qualitative minority-carrier lifetime has been mapped using the EBIC mode of a SEM. This has revealed a reduced photoresponse at the grain boundaries independent of grain size, and also at defect clusters within individual grains. Surface blemishes and etch pits are not important in reducing the cell photoresponse. It appears that the low-temperature processing inherent in semiconductor-insulator-semiconductor solar cells is applicable to polycrystalline material.