Document Type

Article

Publication Date

Summer 9-12-2025

Abstract

Bidirectional photodetection is an emerging functionality in advanced optoelectronic systems, characterized by the ability of a photodetector to respond to the incident light under both forward and reverse biasing voltage. For this aim, a layer of silver oxide (Ag2O) is deposited on CdTe thin films, and then, directly, the fabricated Ag2O@CdTe samples on quartz and n-Si substrates are thermally annealed (from 100 to 400◦C). In general, the surface topography is driven by the post-annealing process; besides that, the crystallinity of Ag2O@CdTe samples is improved at 200◦C. The optical characteristics of transmittance and reflectance spectrophotometric measurements at normal incidence revealed a gradual decline in reflectance alongside increased transmittance with annealing. Bandgap variations were precisely determined using Tauc and Forouhi-Bloomer models, demonstrating a reduction to 1.298 eV at 200◦C and an expansion to 1.673 eV at 400◦C. The fabricated Ag2O@CdTe/nSi heterojunction photodetectors illustrated a bidirectional photoelectric switching behavior with different rise/ fall switching times dependent on the annealing temperature. The annealed devices at 300◦C exhibited stable bidirectional photodetection with enhanced photoresponse, achieving a responsivity of approximately 34.9 mA/ W, a specific detectivity of ~5.26 × 109 Jones, and rapid rise/fall times of 35.1/35.1 ms.

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