Photoresponse Evaluation of a Multiband Self-Driven SnO2/CuO/Si Heterojunction Photodetector Fabricated by Pulsed Laser Deposition

In this Article, a systematic multiband (p-n and n-p-n) analysis of a self-powered SnO₂/CuO/Si heterojunction photodetector was conducted, considering both incident wavelength and light intensity episodes. Furthermore, the microstructural and optical features of the acquired layers were examined. The topography investigations revealed that the average diameters of the nanoparticles were 43.3 and 57.9 nm for the CuO and SnO₂ films, respectively, with corresponding optical bandgaps of 1.98 and 3.75 eV. Additionally, the investigated junctions (n-SnO₂/n-Si, p-CuO/n-Si, and n-SnO₂/p-CuO) demonstrated distinguished figure-of-merits at zero bias voltage, highlighting the self-driven nature of the proposed geometry over the scanned wavelength range. Two primary driving bands were observed at 340 and 625 nm. Particularly, the n-SnO₂/p-CuO structure exhibited a responsivity (R_λ) of 19.37 mA/W and a specific detectivity (D*) of 7.1 × 10¹¹ Jones at 625 nm and 25.3 μW/cm²; these values decreased at 340 nm. The proposed structures also showed reduced figure-of-merits at higher incident light intensities, with an R_λ of 8.9 mA/W and a D* of 3.2 × 10¹¹ Jones observed for the addressed junction at 67.8 μW/cm². The time-resolved profile indicated fast response and recovery times (τ_R/τ_F) of 190 and 250 ms, respectively. An energy-band diagram of a SnO₂/CuO heterojunction photodetector under incident light was also proposed.