Self-biased visible-NIR photodetection enabled via a dual-heterojunction n-MoS2/p-CuO/n-Si design

Abstract

In this study, a comprehensive dual-junction (n-MoS₂/p-CuO/Si and p-CuO/n-Si) evaluation of a self-biased heterostructure was conducted for photodetector applications. Owing to the integration of both junctions, the proposed design offered dual-response functionality, under zero bias, corresponding to the visible (625 nm) and NIR (720 and 808 nm) regions. At zero applied bias, the n-MoS₂/p-CuO/Si heterojunction exhibited a responsivity (R_λ) of 21.04/30.50 mA W⁻¹ and a detectivity (D*) of 1.0 × 10¹⁴/1.5 × 10¹⁴ Jones at incident wavelengths of 625/720 nm; this highlights the self-biased nature of the fabricated design. The attained values were found to be dramatically increased under a 3 V bias, with R₂ values of 0.144 and 0.124 A/W for the n-MoS₂/p-CuO/Si and p-CuO/n-Si heterostructures, respectively. The observed figures-of-merit consistently reduced as the incident light intensity increased, indicating a strong negative correlation, which was further confirmed by the R² value approaching unity (R² = 1). The time-resolved features confirmed response/recovery times of 0.27/0.36 and 0.41/0.48 s, respectively, for the addressed heterostructures, highlighting the suitability of this design for efficient, bias-free photodetection over Vis-NIR wavelengths.