PREPARATION AND PROPERTIES OF SELENIZED CUINSE2 THIN-FILMS

Abstract

Polycrystalline CuInSe2 thin films were prepared by depositing a Cu-In layer, which was sequentially sputtered varying the Cu/(Cu + In) mole ratio, on glass substrate and selenizing with selenium metal vapor in a nitrogen atmosphere. Compositional and structural characterization was carried out by X-ray diffraction, wavelength-dispersive spectroscopy, and scanning electron microscopy. Electrical characterization was carried out by the measurements of Hall voltage and electrical resistivity. Large indium loss occurs in early stage of the selenization process. The selenized films which have mole ratios larger than 0.28 have a chalcopyrite CuInSe2 phase and those that have lower mole ratios have a sphalerite phase. The selenized films containing CuxSe phase have a Cu-rich CuInSe2 phase and those that did not contain CuxSe have an In-rich CuInSe2 phase. By optimizing the sputtering conditions, it is possible to fabricate CuInSe2 thin films which have small secondary phases and an appropriate hole concentration (10(15) approximately 10(16) cm-3) for solar cells