[17p-P11-1~8] 13.9 Compound solar cells

[17p-P11-7] Photoluminescence Studies of Zn-doped CuGaS₂ Thin Films

〇(D)Myeongok Kim¹, Nazmul Ahsan^1,2,3, Nanaki Miura^1,2, Abhishek Gupta^1,3, Yoshitaka Okada^1,2,3, Zacharie Jehl⁴ (1.RCAST UTokyo, 2.Eng. UTokyo, 3.Arts and Sci. UTokyo, 4.IREC)

Keywords:Zn:CuGaS2, Co-sputtering, Photoluminescence

This research studies the optical property of Zn doped CuGaS₂ (CGS) by photoluminescence (PL) analyses for its application to CGS solar cells. Due to the wide bandgap of CGS (E_G = 2.43 eV), buffer layer with wider bandgap, like ZnS (E_G = 3.7 eV), is considered for solar cells, and Zn from ZnS can diffuse into CGS surface. This study aims to replicate the interface between CGS and ZnS. Zn:CGS films were fabricated on Mo coated SLG substrate by co-sputtering method. Incorporation of Zn into CGS was confirmed by the shift of CGS (112) plane’s diffraction peak based on X-ray diffraction analyses. Undoped CGS showed PL signal from 2.47 eV and 2.30 eV, which may attribute to band-to-band transition and intrinsic acceptor type defect, V_Cu, respectively. With Zn doping, PL signal from 2.30 eV disappeared, and new transition at 2.03-2.10 eV was observed. For the formation energy of Zn_Cu is known to be lower than that of V_Cu, it is assumed that doped Zn substitutes Cu vacancy (V_Cu) and forms donor type antisite Zn_Cu.