SEQUENTIAL PROCESSES FOR THE DEPOSITION OF POLYCRYSTALLINE CU(IN,GA)(S,SE)(2) THIN-FILMS - GROWTH-MECHANISM AND DEVICES

Sequential processes for the fabrication of polycrystalline Cu(In,Ga)( S,Se)(2) thin films using (In,Ga)(x)(S,Se) precursors are presented an d discussed. Depending on the deposition conditions and the source mat erial, different InxS precursor films for the formation of CuInS2 can be obtained. For In/(In + Cu)>0.5 the reaction pathway of CuInS2 thin films follows the Cu2S-In2S3 pseudobinary tie line after the indiffusi on of Cu and S independent of the composition of the InxS precursor. A Cu-rich step resulting in the segregation of CuS is accompanied by a recrystallization of the entire film. The coverage of CuInS2 with CuS is more complete for the sequential process as compared to codeposited thin films. The device performance of devices based on Cu(In,Ga)(S,Se )(2) grown by codeposition and by sequential processes is comparable.