Temperature-dependent phase formation of CuInSe2 for self-biased, broadband Si/CuInSe2 heterojunction photodetector

Owing to the numerous applications including optical communication, night vision, remote sensing, and security monitoring, a great interest has emerged in the development of the NIR (near-infrared) photodetectors. In this study, the self-biased Si/CuInSe ₂ heterojunction photodetectors have been developed and the annealing temperature has been optimized. CuInSe ₂ thin films have been prepared using the sequential elemental layer deposition followed by annealing at 550, 600, and 650 °C. The CuInSe ₂ annealed at 550 °C and 650 °C revealed the mixed-phase formation corresponding to CuInSe ₂ (tetragonal) and Cu ₇Se ₄ (Cubic). The CuInSe ₂ annealed at 600 °C confirmed the transition from mixed-phase to single-phase CuInSe ₂ tetragonal structure. The impact of annealing temperature-dependent phase formation on the optoelectronic characteristics of Si/CuInSe ₂ heterojunction has been studied. The Si/CuInSe ₂ heterojunction formation and photodetection in the self-biased mode have been investigated under varying Halogen light intensity and wavelength-dependent light. The highly sensitive, broadband spectral response and enhanced detectivity in the self-biased mode have been explored in the vicinity of varying annealing temperatures. The optimum Si/CuInSe ₂ heterojunction photodetector performance was achieved at 600 °C possessing the sensitivity, detectivity, and LDR up to 2.4 × 10 ³, 0.05 × 10 ¹² Jones, and 68 dB under Halogen light exposure and 0.8 × 10 ⁴, 0.55 × 10 ¹² Jones and 79 dB under 980 nm light. The present study provides useful insight into the Si/CuInSe ₂ heterojunction development as an optoelectronic device providing the correlation between the fundamental characteristics of CuInSe ₂ and its development as a broadband photodetector possessing excellent device performance in the NIR range.