FABRICATION OF CIGS THIN FILM SOLAR CELLS BY SELENIZATION OF METALLIC LAYERS

Abstract

Cu-In-Ga (CIG) metallic precursor thin films were fabricated on Mo-coated soda-lime glass (SLG) substrates to imitate the precursor growth by co-sputtering from metallic targets. Selenium (Se) was incorporated into the precursors by means of Cu-Se co-evaporation and Se vapor. It was found that Cu, In and Ga could not be deposited simultaneously due to lower melting point of In that caused the agglomeration of the precursors. The sequential evaporations of Cu-Ga followed by In were then applied. The substrate temperature was optimized for the depositions of Cu-Ga and In that directly affected the formation of the alloying precursors. The vacuum annealing of precursors at 450°C was employed. The duration of the Cu-Se flux and the annealing time were among the important varying parameters. The formation of the CIGS layer and its chalcopyrite phases were investigated by FESEM and XRD, respectively. The CIGS thin film solar cells were also fabricated by standard procedures and tested for their I-V characteristics and spectral response by quantum efficiency measurements. The best efficiency of the CIGS solar cells obtained from the absorber fabricated by this method is 13.2%.