Unraveling the Properties of Interdigital Electrode-Based γ-In₂Se₃ Photodetectors for Optimal Performance

We successfully deposited In2Se3 films on the interdigital electrode (IDE) substrates using the radio frequency (RF)-magnetron sputtering method with optimized parameters. The formation of high-quality <inline-formula> <tex-math notation="LaTeX">$\gamma $ </tex-math></inline-formula>-In2Se3 using X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), and energy dispersive spectroscopy (EDS) is explored. Subsequently, we fabricated <inline-formula> <tex-math notation="LaTeX">$\gamma $ </tex-math></inline-formula>-In2Se3-based photodetectors on indium tin oxide (ITO)-coated IDE using optimized parameters. The detailed investigation focused on the influence of IDE spacing, bias voltage, and light intensity on the photodetector properties. The photodetector fabricated with an IDE spacing of <inline-formula> <tex-math notation="LaTeX">$335~\mu $ </tex-math></inline-formula>m exhibited outstanding properties, including the highest photoresponsivity of <inline-formula> <tex-math notation="LaTeX">$14.8~\mu $ </tex-math></inline-formula>A/W and detectivity of <inline-formula> <tex-math notation="LaTeX">$31.3 \times 10^{{7}}$ </tex-math></inline-formula> Jones. It also demonstrated a fast rise time of 99 ms and a decay time of 61 ms. In the bias voltage variation study, the <inline-formula> <tex-math notation="LaTeX">$\gamma $ </tex-math></inline-formula>-In2Se3-based photodetectors exhibited a linear relationship between the change in current and the bias potential, indicating the formation of ohmic contact between <inline-formula> <tex-math notation="LaTeX">$\gamma $ </tex-math></inline-formula>-In2Se3 and ITO electrodes. Examining light intensity photoresponse, we varied the power density of light from 5 to 30 mW/cm2. We observed a direct proportionality between the generated photocurrent and the incident light intensity. However, at higher light intensities, there was a decrease in photodetectivity from <inline-formula> <tex-math notation="LaTeX">$3.97\times 10^{{8}}$ </tex-math></inline-formula> to <inline-formula> <tex-math notation="LaTeX">$1.16 \times 10^{{8}}$ </tex-math></inline-formula> Jones and a reduction in photoresponsivity from 33.36 to <inline-formula> <tex-math notation="LaTeX">$9.73~\mu $ </tex-math></inline-formula>A/W for the <inline-formula> <tex-math notation="LaTeX">$\gamma $ </tex-math></inline-formula>-In2Se3-based photodetectors. In conclusion, the photodetector properties of <inline-formula> <tex-math notation="LaTeX">$\gamma $ </tex-math></inline-formula>-In2Se3-based devices are critically influenced by IDE spacing, bias voltage, and light intensity.