Ultraviolet Photodetectors Based on 4H-SiC With Honeycomb-Like Light-Trapping Structures

Silicon carbide (SiC), as a wide-bandgap semiconductor, exhibits significant potential for visual-blind ultraviolet (UV) detection due to its excellent material properties. To further improve the performance of SiC UV detectors, we introduce the honeycomb-like light-trapping microstructures at the surface of SiC, which are fabricated by using a facile and efficient photoelectrochemical (PEC) etching method. The mechanism underlying the formation of the light-trapping microstructures is carefully investigated. It is found that the anisotropic etching is dependent on the crystal orientation of SiC. After the formation of the honeycomb-like light-trapping microstructures, optical characterizations reveal substantial suppression of UV reflection and enhanced absorption due to the increased light path and multiple internal reflections. The self-powered SiC UV photodetector with the light-trapping microstructures shows a peak responsivity of 0.187 A/W at the wavelength of 290 nm, which corresponds to an external quantum efficiency of 80%. This self-powered photodetector also demonstrates excellent performance in imaging and optical communication. The low-cost, scalable, and selective etching for the formation of the light-trapping microstructures has important implications for the development of high-performance SiC-based optoelectronic devices.