[6a-S21-1~9] 13.10 Compound solar cells

▲ [6a-S21-8] Micro-photoluminescence study of the polycrystalline CuGaSe₂ thin-films evaporated by three-stage process

〇Muhammad Monirul Islam¹, Shenghao Wang¹, Shogo Ishizuka², Hajime Shibata², Shigeru Niki², Katsuhiro Akimoto¹, Takeaki Sakurai¹ (1.Tsukuba Univ., 2.AIST)

Keywords:chalcogenide solar cells, thin films, deep level

Micro photoluminescence (µ-PL) was performed to investigate radiative and non-radiative transitions in the wide-gap CuGaSe₂ material.Polycrystalline CuGaSe₂ thin-films with 2 μm of thickness were grown over Mo-coated soda lime glass (SLG) substrates through three-stage co-evaporation process. µ-PL was performed with a confocal laser scanning microscope using a 635 nm line of a diode laser. A peak found around 1.5 eV is in consistent with results of other researchers, and considered as a donor-acceptor pair transition (DAP1). An emission at low energy side with asymmetric and broadened peak around 1.3 eV was observed and assigned as DAP2 based on its power dependence. In addition, a new broadened emission around 0.9~1.1 eV was found and assigned as a deep donor-acceptor emission, DDA. Considering the same acceptor level as for DAP2, donor level involved with this emission is located around 600 meV below E_C which may be tailored down to 800 meV.