Opto-electrical evaluation of visible blind fast-response nanostructured SnO2/Si photodetector

Abstract

In this study, a nanostructured tin(IV) oxide (SnO₂)/Si heterojunction UV photodetector was fabricated in response to laser pulses attained via pulsed laser deposition (PLD). In particular, the photo-detection mechanisms of the proposed devices were thoroughly investigated considering multiple-profile dependency, namely, laser pulses, spectral response, and incident power. In detail, particle diameters of 25 and 41 nm with a bandgap alteration of 0.2 eV and a cut-off phenomenon at around 335 nm occurred as a result of an increase in the number of pulses from 300 to 700. The optimum photodetector (at 700 pulses, λ₃₄₀ nm, and 10 mW cm⁻²) revealed a responsivity (R_λ) and external quantum efficiency (EQE) of 32.9 mA W⁻¹ and 120.2, respectively. Furthermore, a descended photocurrent behavior from 330 to 63.9 (μA) was observed at wavelengths of 340 and 625 nm with a visible light rejection ratio of 516%, indicating the visible blind characteristic of the proposed geometry. This was also observed at an extremely low bias potential (0.01 V). The incident power profile demonstrated an inversely proportional correlation to R_λ and EQE, with values 37.8 mA W⁻¹ and 137.7 at 6 mW cm⁻², respectively. Of the fabricated devices, the photodetector performance attained at 700 pulses, λ₃₄₀ nm, and 10 mW cm⁻² depicted a substantially rapid time-resolved characteristic with a rise and fall time of 0.29 and 0.31 s, respectively.