Small Secondary Phase Research Articles

Preparation and properties of selenized CuInSe 2 thin films

Abstract Polycrystalline CuInSe 2 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 CuInSe 2 phase and those that have lower mole ratios have a sphalerite phase. The selenized films containing Cu x Se phase have a Cu-rich CuInSe 2 phase and those that did not contain Cu x Se have an In-rich CuInSe 2 phase. By optimizing the sputtering conditions, it is possible to fabricate CuInSe 2 thin films which have small secondary phases and an appropriate hole concentration (10 15 ≈ 10 16 cm −3 ) for solar cells