Document Type

Article

Publication Date

Winter 11-9-2025

Abstract

This investigation explores the influence of substrate temperature on the photodetection characteristics of indium-doped cadmium selenide (In:CdSe) thin films, addressing a critical gap in understanding how deposition parameters affect the optoelectronic properties of these materials. The study systematically analyzes the effects of substrate temperatures ranging from 30 °C to 250 °C on thermally evaporated In:CdSe films through comprehensive structural and morphological characterization. X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM) analyses reveal enhanced crystallinity and well-defined nanostructured surface morphology up to 100 °C, with distinct nanorod formations emerging at 200 °C. Energy dispersive X-ray spectroscopy (EDX) confirms the selenium-rich composition of the films and demonstrates variations in the Se/Cd stoichiometric ratio as a function of substrate temperature. These structural modifications significantly impact optical properties, as evidenced by spectrophotometric measurements in the UV–visible-NIR spectrum. The optical bandgap exhibits substantial broadening, reaching 2.38 eV at 250 °C through absorption spectrum analysis. Photodetection performance evaluation of In:CdSe/p-Si heterojunction devices under polychromatic illumination (20–100 mW/cm2) demonstrates optimal performance at a 100 °C substrate temperature, achieving responsivity of 86 mA/W, specific detectivity of 1.28 × 1011 Jones, signal-to-noise ratio of 6113, and rapid response times of 28.3 ms (tr) and 30 ms (tf). Spectral selectivity assessment of the visible range confirms the practical viability of these photodetectors.

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