Effect of substrate temperatures on evaporated In2S3 thin film buffer layers for Cu(In,Ga)Se2 solar cells

• Published in: Thin solid films 2013-11, Vol.547, p.22-27
• Main Authors: Zhong, Zhao Yang, Cho, Eou Sik, Kwon, Sang Jik
• Format: Article
• Language: English
• Subjects: Applied sciences; Atomic ratio; Buffer layers; CIGS; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; COPPER INDIUM SELENIDE; COPPER SELENIDE; Cu(In,Ga)Se2 solar cell; DEPOSITION; Energy; Evaporation; Exact sciences and technology; Grain size; GRAIN SIZE AND SHAPE; In2S3 buffer layers; Natural energy; Optical band gap; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Photovoltaic cells; Photovoltaic conversion; Physics; Scanning electron microscopy; Solar cells; Solar cells. Photoelectrochemical cells; Solar energy; Structure and morphology; thickness; Substrate temperature; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thermal evaporation process; Thin film structure and morphology; THIN FILMS
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2013.05.071

For the realization of vacuum in-line process in the fabrication of Cu(In,Ga)Se2 (CIGS) solar cells, In2S3 thin film buffer layers for CIGS have been deposited on glasses and CIGS layers with a thickness of about 650Å by thermal evaporation process. During the thermal evaporation, the temperature of the substrate was varied from room temperature to 500°C by heating and the grown In2S3 films were investigated and analyzed in terms of the optimized buffer layer for CIGS solar cells. From the results of scanning electron microscope and X-ray diffraction, the In2S3 thin film deposited at a higher substrate temperature showed the larger grain size and the films have amorphous structural characteristics. Although the structural characteristics such as the atomic ratio of In to S and transmittance of the In2S3 thin films were not proportional to temperature, it was possible to obtain the large optical band gap of In2S3 films of about 3.8–3.9eV enough to be used as the buffer layer of CIGS. •In2S3 films were deposited at various substrate temperatures by thermal evaporation.•The atomic ratio of In to S in the In2S3 film has the highest value at 300°C.•The In2S3 film has a band gap of about 3.8eV because of its amorphous structure.•The In2S3 film is expected to be used as a buffer layer by in-line vacuum process.