An interface-enabled dual response in a self-biased n-Bi2S3/porous Si/p-Si heterostructured photodetector

Abstract

In this study, the fabrication process of a dual visible-NIR self-biased n-Bi₂S₃/porous Si/p-Si heterojunction photodetector using a rapid pulsed laser deposition (PLD) approach is systematically elucidated. The morphological observations revealed the porous nature of the fabricated porous Si layer with a pore diameter of ∼66 nm along with incorporated Bi₂S₃ nanoparticles (∼38 nm), while the optical investigation revealed a band gap of 1.7 eV. The proposed geometry exhibited a low saturation dark current (∼35 nA) along with rectification on the order of 10²; this indicates a well-oriented junction along with the active role of the porous Si. The fabricated heterojunction demonstrated a dual response (575 and 720 nm) with responsivity values of 404 and 226 mA W⁻¹ at 5 V, respectively; these values were found to be decreased to 460.05 and 251 µA W⁻¹, indicating a strong absorption in the active layer at 575 nm along with porous Si-related enhanced light trapping. A linear dependency was established between the evaluated figures-of-merit and the incident light intensity, with R² values approaching ∼1. The fabricated device exhibited fast switching behavior with a rise/fall time of 101/116 ms and 124/163 ms at 575 and 720 nm, respectively, while a stable time-resolved characteristic over 30 days was also perceived.