Controlled Localized Phase Transition of Selenium for Color-Selective Photodetectors

Color-selective photodetectors are widely applied in several fields; however, they suffer from complex fabrication and low resolution. Herein, we propose a simple and convenient design to achieve a logical color-selective heterojunction photodetector composed of CdS and Se with a crystalline/amorphous mixed state. The as-deposited amorphous Se top layer in the heterojunction is partly transformed to trigonal crystalline Se by localized in situ phase transformation during annealing. As these two heterojunctions have different photoresponses under the same wavelength, the integrated device can accurately identify red, green, and blue light via logical judgment. Finally, the device exhibits high recognition ability in actual tests. This work provides a potential development of high-resolution color-selective photodetectors for visible light communication and logical photoelectric devices.