Exploring the relationship between reaction temperature and photodetection properties in Sb2Se3 thin film-based devices

Abstract

This paper focuses on optimizing the reaction temperature of Sb₂Se₃ thin films for photodetector applications. The films were grown using a two-stage method on glass substrates. Structural analysis revealed the formation of the orthorhombic Sb₂Se₃ phase along the (020) plane, and increasing the reaction temperature up to 400 °C improved the crystal quality. Notably, the most promising structural properties were achieved for Sb₂Se₃ thin films reacted at 380 °C. Raman spectra confirmed the presence of tetragonal and amorphous selenium, along with Sb₂Se₃. Morphological analysis showed that a horizontally aligned rod morphology developed as the Sb₂Se₃ thin film grew, with the rod sizes increasing as the reaction temperature reached to 400 °C. X-ray photoelectron spectroscopy (XPS) revealed the formation of Sb-Se and Sb-O bonds, along with the presence of unreacted oxygen atoms near the surface of Sb₂Se₃ thin films reacted at 340 °C. Photoluminescence data indicated a bandgap value of 1.24 eV for Sb₂Se₃ films reacted at 380 °C. The current-voltage (I-V) curves exhibited a linear dependence for all Sb₂Se₃-based devices, suggesting ohmic contact between the films and the electrodes. The fastest photoresponse was observed for the photodetector annealed at 380 °C, with rise and fall times of 26 ms and 40 ms, respectively. Additionally, the highest responsivity (R = 8.0 × 10^–4 A/W), detectivity (D* = 3.8 × 10⁶ Jones), and external quantum efficiency (EQE = 16.3%) were achieved by the same device, indicating that the optimal reaction temperature for Sb₂Se₃ thin films and their photodetector applications is approximately at 380 °C.