NEAR-FIELD SCANNING OPTICAL MICROSCOPY STUDIES OF CU(IN,GA)SE-2 SOLAR-CELLS

A near-field scanning optical microscope (NSOM) is used to study the l ocal photoresponse of Cu(In,Ga)Se-2 thin film solar cells. The grain b oundaries of the small grains (<1 mu m) show some reduction in photore sponse; however the photoresponse is significantly reduced near most c revices separating large grains (>10 mu m). In addition, NSOM images s how response variations from grain to grain and areas of reduced photo response which have no corresponding topography. Photovoltage imaging of the cleaved side of the solar cells reveals the depth and nonunifor mities of the actual p-n junction. It is found that the response of th e p-n junction varies on a 0.5 mu m length scale. (C) 1997 American In stitute of Physics.