[20p-P14-1~23] 13.10 Compound solar cells

[20p-P14-7] Chemical Composition Dependence of Photoluminescence from Cu₂ZnSnS₄ Thin Film

〇Kunihiko Tanaka¹, Shinya Miura¹, Yoshiharu Takamatsu¹ (1.Nagaoka Univ. Tech.)

Keywords:Cu2ZnSnS4(CZTS),Photoluminescence,chemical composition dependence

Photoluminescence from Cu₂ZnSnS₄ (CZTS) thin films, which was nearly stoichiometric, was investigated. The CZTS thin films were prepared by sulfurizing metal precursors which were deposited by sputtering method. PL spectra depend on temperature and excitation intensity was investigated. The thin films were excited by second harmonics of CW Nd³⁺:YVO₄ laser (532 nm), and PL was dispersed by f=60mm polychromator and detected by Si-CCD. Three types of broad spectrum were observed. The PL spectra from all samples contained some peaks at ~1.2 eV, ~1.3 eV and 1.5 eV, and peak energies of the spectra were 1.2 eV (Group A=Zn/Sn>1), 1.3 eV (Group B=Zn/Sn<1, Cu/(Zn+Sn)<1), 1.5 eV (Group C= Zn/Sn<1, Cu/(Zn+Sn)>1), respectively. The origin of the peaks of ~1.2 eV, ~1.3 eV and 1.5 eV, were assigned to band-to-impurity (BI), band-to-tail (BT), band-to-band (BB), respectively. From spectra of Group B, estimated potential fluctuation was 25~30 meV.