Significance of rapid thermal annealing and its ramp rate effect on the properties of monoclinic CTS thin films

摘要

The rapid thermal annealing/sulfurization process has been widely used for the fabrication of absorber films in the two-stage process, which can simplify the thin film fabrication process. In the present investigation, Cu_2SnS_3 (CTS) thin films were deposited by the two-stage process which involved sputtering and rapid thermal annealing process (RTP). The CTS thin films were deposited at different ramp rates from 10 ℃/min - 50 /℃min and the sulfurization temperature of 520 ℃. The XRD results confirmed the dominant monoclinic CTS phase with high crystalline quality. The Raman analysis of the sulfurized films exhibited the Raman modes at 295 cm~(-1) and 354 cm~(-1), and these modes confirmed the monoclinic phase of CTS. All the M-CTS films showed Cu/Sn ratio (Cu-poor) close to stoichiometric composition and exhibited compact morphology with good grain size. The optical bandgap values and absorption coefficient of M-CTS firms were found to be around 0.93 eV-0.95 eV and ＞10~4 cm~(-1), respectively.