Effects of Cu+ ion implantation on band gap and Raman shift of Cu2ZnSnS4 thin films

Abstract

In this study, shifts in the band gap and position of the main Raman peak of Cu2ZnSnS4 (CZTS) thin films were analyzed. These shifts were caused by residual tensile strain originating from artificially implanted Cu+ ions on the CZTS thin films. Cu+ ions were implanted at various doses in the CZTS thin films. The residual strain increased linearly as the logarithmic dose of Cu+ ions increased. According to the Raman spectrum analysis, the CZTS thin films had kesterite order structures. The band gap and the shift of the main Raman peak, P1, are linear functions of the residual strain and are linearly related to each other. A larger residual strain led to larger decreases of 1.50 eV and 337.5 cm−1 in the band gap and position of the main Raman peak (P1), respectively.