Influence of annealing temperature on properties of Cu(In,Ga)(Se,S) _2 thin films prepared by co-sputtering from quaternary alloy and In_2S_3 targets

摘要

Pentanary Cu(In,Ga)(Se,S)_2 (CIGSS) thin films were deposited on soda-lime glass substrate by co-sputtering quaternary alloy, and In _2S_3 targets. In this study, we investigated the influence of post-annealing temperature on structural, compositional, electrical, and optical properties of CIGSS films. Our experimental results show that the CIGS quaternary target had chalcopyrite characteristics. All CIGSS films annealed above 733 K exhibited a polycrystalline tetragonal chalcopyrite structure, with (1 1 2) preferred orientation. The carrier concentration and resistivity of the resultant CIGSS layer annealed above 763 K was 4.86×10~(16) cm~(-3) and 32 Ω cm, respectively, and the optical band-gap of the CIGSS absorber layer was 1.18 eV. Raman spectral analysis demonstrated the existence of many different phases, including CuInSe_2, CuGaSe _2, and CuInS_2. This may be because the vibration frequencies of InSe, InS bonds are similar to the GaSe and GaS bonds, causing their absorption bands overlap.