Preparation of Polycrystalline Cu(In,Ga)Se_2 Thin Film with Nano-metal Oxide:the Chemical Reaction Process and Its Properties

Polycrystalline Cu(In,Ga)Se 2(CIGS) thin film was prepared by non-vacuum method with nano-metal oxide as starting materials.The evolution of the composition and structure during the preparation process was investigated by field emission scanning electron microscope,high resolution transmission electron microscope,energy dispersive analysis and X-ray diffraction.The properties of CIGS film was characterized using Hall Effect tester and absorption spectroscopic analysis.The results show that the nano-metal oxide is consist of CuO,In 2 O 3,Ga 2 O 3 and copper-indium,copper-gallium binary alloy oxides.The metal oxides gradually transform into Cu 11 In 9 and Cu 9 In 4 during the reduction reaction.Moreover,it forms a large number of pores,which is benefit for the selenide reaction.The selenium vapors enter the film along the pore,react with the reduction product and form CIS and CGS in the selenide process.Then,the polycrystalline CIGS film with the chalcopyrite structure forms.The carrier concentration,mobility and the resistivity of CIGS film are about 2.3×10 15 cm-3,217 cm 2 /(V.s) and 36.cm,respectively.The obtained thin film is a p-type semiconductor with a bandgap of about 1.15 eV.