ANNEALING EFFECT IN OXYGEN ATMOSPHERE ON THE OPTICAL AND ELECTRICAL PROPERTIES OF CuInS CuInS2 THIN FILMS

摘要

CuInS CuInS2 thin films were deposited by single source vacuum thermal evaporation method on glass substrates. These films have been annealed under different partial pressures of oxygen at 200°C for one hour. The morphological, optical and electrical properties were studied according to oxygen concentration. The surface morphology is observed using the scanning electron microscope; it has showed a net improvement of the homogeneity of the surface when oxygen concentration is increased. The incorporation of the oxygen in CuInS CuInS2 thin films increases the conductivity by creating donor levels in the band gap. In the same way, the effect of the oxygen on the optical absorption and reflection as well as on the width of the forbidden band has been analyzed by spectrophotometer equipped with an integrating sphere that takes into account the diffused part of the light. The reflection decreases strongly after annealing under secondary vacuum then an increase of this latter with oxygen pressure is observed without reaching its initial value. The absorption coefficient is increased and the energy gap is decreased with oxygen concentration.