Semipolar (11(2)over-bar2) AlGaN-Based Solar-Blind Ultraviolet Photodetectors with Fast Response

The high-quality semipolar (11 (2) over bar2) AlGaN epitaxial films have been obtained on m-plane sapphire by metal-organic chemical vapor deposition. X-ray rocking curve measurements show the full-width at half-maximums of semipolar (11 (2) over bar2)-oriented AlGaN films are 0.357 degrees and 0.531 degrees along [11 (23) over bar](AlGaN) and [1 (1) over bar 00](AlGaN), respectively. The fabricated semipolar AlGaN metal-semiconductor-metal solar-blind ultraviolet (UV) photodetector (PD) exhibits a high responsivity of 1842 A/W. The fast response and reliability of the UV PD are ensured via fast switching with a rise and decay time of 90 ms and 53(720) ms, respectively. The UV PD exhibits a significant reduction in the dark current, that is, from 100 mu A to 780 fA at 10 V, using a simple wet chemical etching to modify the surface properties of materials. The photo-to-dark-current ratio value of the etched UV PD reaches 4 orders of magnitude higher than the unetched UV PD under 270 nm illumination. These are attributed to the fact that KOH wet etching assists in eliminating the surface states and reconstructing the surface oxides. This work might provide a new potential for the development of solar-blind UV PDs with high performance.

Automated summary

In this study, high-quality semipolar AlGaN epitaxial films were successfully obtained on m-plane sapphire substrates by metal-organic chemical vapor deposition. The fabricated semipolar AlGaN metal-semiconductor-metal solar-blind ultraviolet photodetector exhibited high responsivity and fast response, with significantly reduced dark current through a simple wet chemical etching method. This work shows potential for the development of high-performance solar-blind ultraviolet photodetectors.