The formation of CuInSe2 thin films by rapid thermal processing

Formation of polycrystalline thin film CuInSe₂ was achieved by the rapid thermal processing of vacuum-deposited copper, indium, and selenium. Films were fabricated and characterized in three composition regions: copper-poor (approximately 20 at.% Cu). stoichiometric (25 at.% Cu) and copper-rich (approximately 28 at.% Cu). Characterization results including X-ray diffraction analysis, electron probe for microanalysis, scanning electron microscopy, and optical reflection and transmission measurements are presented. The results show that nearly single-phase material has been formed from co-deposited precursors with a post-deposition annealing time of less than 2 min. The films have smooth morphologies amenable for photovoltaic device fabrication, optical absorption coefficients in the high 10⁴ cm⁻¹ range, and an optical band gap of 1.0 eV.