Enhancement of high-temperature solar-blind UV photodetector performance on 4H–SiC substrates by deposition of ultrawide bandgap diamond films

Abstract

High-temperature operation and solar-blind ultraviolet (UV) sensitivity remain significant challenges for 4H–SiC-based photodetectors, limiting their performance in harsh environmental conditions. To address these issues, the deposition of ultrawide bandgap diamond films is employed to enhance the high-temperature performance of solar-blind UV photodetectors. Diamond films of varying thicknesses were deposited on 4H–SiC substrates using microwave plasma chemical vapor deposition. The photodetector achieves a maximum room-temperature responsivity of 0.12 A/W under 220 nm illumination with a 15 V bias, nearly 15 times higher than that observed in a 4H–SiC-only photodetector. Furthermore, the photodetectors exhibit exceptional UV/visible rejection ratios of 645, a photo-to-dark current ratio of 5.34 × 10³, and a detectivity of 2.55 × 10¹² Jones at room temperature. As the operating temperature increases, both the 220 nm responsivity and UV/visible rejection ratio improve, reaching approximately 0.6 A/W and 980 at 200 °C, respectively, which are 30 and 245 times higher than those of the pure SiC photodetector. The diamond films significantly enhance the solar-blind UV performance of SiC-based photodetectors at high temperatures.