Self-powered γ-In2Se3/p-Si heterojunction for photodetection: exploring humidity and light intensity dependent photoresponse

Abstract

In this study, high-quality γ-In₂Se₃ thin films were successfully deposited on p-Si substrates via the RF sputtering technique. Structural characterization using XRD and Raman spectroscopy confirmed the formation of the hexagonal γ-phase of In₂Se₃ film. FESEM analysis revealed the presence of small, homogeneous, and well-defined grains in the prepared γ-In₂Se₃ film. EDS analysis confirmed the stoichiometric composition (∼ 2:3) of the In₂Se₃ films. XPS further validated the presence of In, Se, and Si elements in the deposited films. Band gap analysis using UV-visible spectroscopy yielded a value of 1.96 eV for the γ-In₂Se₃ film. Integration of γ-In₂Se₃ with p-type Si enhanced photoresponsivity of 47.9 mA/W, photosensitivity of 282, and photo detectivity of 8.45 × 10¹⁰ Jones. The self-powered γ-In₂Se₃/p-Si heterojunction-based photodetector exhibited rapid rise time attributed to the type II band alignment structure, facilitating efficient electron-hole pair separation and minimizing recombination. Furthermore, humidity and light intensity-dependent photodetector properties of γ-In₂Se₃/p-Si heterojunction photodetector were also investigated. An increase in photocurrent from 271 to 291 µA was observed with rising humidity levels, indicating the device's sensitivity to humidity variations. Furthermore, light intensity dependence studies revealed a linear relationship between photocurrent and incident light intensity, demonstrating the device's reliable response across various illumination levels.