Epitaxial silicon solar cells on metallurgical silicon

Solar cell structures have been prepared by the successive deposition of p-type and n⁺-type silicon layers on p⁺- type metallurgical-grade silicon substrates using the thermal reduction of trichlorosilane containing appropriate dopants. When metallurgical-grade silicon plates prepared by the solidification technique were used as substrates, the effects of grain boundaries on the dark current-voltage characteristics and conversion efficiency of solar cells were found to be reduced by increasing the dopant concentration in the p-layer. Using zone-refined metallurgical-grade silicon as the substrate, conversion efficiencies up to 8% have been obtained.