Traditional photodetectors generally have the limitation of single-band detection, making it difficult to effectively distinguish multi-wavelength optical signals. In this study, by constructing a heterojunction structure of Cu₂O and α-Ga₂O₃, a photodetection device with wavelength resolution capability was innovatively fabricated. Through the synergistic effect of the built-in electric field of the p-n junction and the semiconductor/electrolyte junction, this detector exhibits unique dual-wavelength response characteristics under 0 V. It generates photocurrents in opposite directions for ultraviolet light at 255 nm and 365 nm, respectively. Experimental data shows that the responsivity of this device reaches 3.6 mA/W under 255 nm ultraviolet light and -0.15 mA/W at 365 nm. Based on this bidirectional current characteristic, a differential signal encryption communication system was further designed and simulated, effectively avoiding the problem of signal interference in traditional optical communication. The research indicates that photodetectors composed of materials with different band gaps provide an effective way to distinguish different illumination bands, and their bidirectional current characteristics show broad application prospects in the fields of optical communication and optoelectronic devices.
Wang et al. (Fri,) studied this question.