All-diamond transparent solar-blind UV photodetector with thin boron-doped diamond film as electrodes

This work demonstrates an all-diamond solar-blind ultraviolet photodetector employing a heavily boron-doped diamond (BDD) thin film as a transparent electrode. This monolithic structure overcomes the optical blocking inherent to traditional metal electrodes while maintaining excellent interfacial characteristics. Under 222 nm illumination and a 10 V bias, the device achieves a responsivity of 49.8 mA/W, approximately one order of magnitude higher than that of a Ti-electrode counterpart. The UV-to-visible rejection ratio reaches 4.54 × 10⁴, accompanied by a high photocurrent-to-dark current ratio of 441.8. Dynamic response measurements reveal fast rise and decay times of 0.13 s and 0.03 s, respectively, significantly outperforming the metal-electrode device. These results highlight the significant advantages of the all-diamond BDD electrode in responsivity, speed, and spectral selectivity, providing a promising approach for high-performance solar-blind UV detection.