ILGAR CuInS2 films from various preparation conditions

CuInS2 thin films were prepared by ion layer gas reaction (ILGAR) method using C2H5OH as solvent, CuCl and InCl3 as reagents and H2S gas as sulfuration source. The effects of cationic precursor concentration and numbers of dipping cycles on characteristics of CuInS2 film were investigated. The results shows that the chalcopyrite CuInS2 with near stoichiometry can be deposited as [In3+] ≤ 0.05 M and [Cu+] ≤ 0.078M ([Cu+]/[In3+] = 1.55), while CuxS segregation phase appears with further increasing cationic concentration. Its deposition rate is close to constant as cationic concentration is fixed, and nonlinearly increases with increasing the cationic concentration. CuInS2 thin film derived from lower cationic concentration is uniform, compact and good in adhesion to the substrates. The absorption coefficient of CuInS2 thin films is larger than 104 cm−1, and the optical band gap Eg is 1.30∼1.40 eV and has a slight fall with increase of the cationic concentration. The dark resistivity decreases from ∼50 to ∼10 Ω cm and the carrier concentration ranges over 1016 cm−3.