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 (Rλ) 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 Rλ 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 (τR/τF) of 190 and 250 ms, respectively. An energy-band diagram of a SnO2/CuO heterojunction photodetector under incident light was also proposed.