Crystal Growth And Control Research Of CIGS Thin Films

The Copper Indium Gallium Selenium(C uIn1-x Gax Se2 solar cells, short for CIGS) thin film solar cell is a new kind of clean solar, which is regarded as one of most promising solar cells in the world due to its low c ost, high conversion efficiency, stable performance, high radiation resistance and wide spectral response range. Recently, the conversion efficiency of CIGS thin film solar cell set up a new record of 20.8%, which was created by Germany Center for solar energy and hydrogen research(ZSW) laboratory cooperated with Manz in October 2013.Ⅰ-Ⅲ-Ⅳ compounds semiconductor CIGS thin film is the core layer of CIGS thin film solar cell. C halcopyrite structure and P-type semiconductor of CIGS is a direct band gap semiconductor, with 105cm-1 absorption and it is the most suitable for thin film as lo ng as the thickness can reach 1.5 ~ 3μm.In this experiment, we prepared CIGS thin film by using one-step thermal evaporation method and mid-frequency magnetron sputtering. Using one-step thermal evaporation method to successfully prepare CIGS thin film on glass and Mo substrate, and the influences of substrate temperature on the crystal growth of CIGS thin film were investigated.The results show that the stoichiometric composition of CIGS thin films is uniform and homogeneous on glass and Mo substrates, and the films present the growth of flake structure and columnar structure, while absorption coefficient and band-gap are more pronounced in flake- like films compared to column- like films. Mid- frequency magnetron sputtering using a single quaternary-CIGS target in stoichiometric proportion and the influences of substrate temperature and power on the structural and property of CIGS thin films were investigated. The results show that the property of CIGS thin films achieved optimal with the substrate temperature increases at 250℃,while the size of crystal reached 1μm, with high absorption coefficient(close to 105cm-1),and with the band- gap reached 1.41 eV.