Influence of cell design on processing and performance for InP based solar cells

A comparison of homojunction and ITO/InP cells grown on the same substrate material is presented. Both cell types use a base region of MOVPE p-InP, grown under the same conditions. Cells of 4 cm² in area of both types have been fabricated. Issues relating to the cell processing including junction formation and grid fabrication, are discussed. Although the homojunction cells currently exhibit superior performance in terms of efficiency and open circuit voltage, there exists much scope for optimization, particularly for the ITO/InP cells. Electrical characterization suggests a buried n⁺ /i/p structure for the ITO/InP cells, with i-layer thickness dependent on both processing and subsequent treatment. Post fabrication treatment of the cells is considered, in particular handling and interconnection. Ultrasonic bonding of foil interconnects appears to be a promising technique for both cell types