Inclination of screw dislocations on the performance of homoepitaxial GaN based UV photodetectors

We analyze the dislocation-assisted charge carrier transport and effective photocurrent generation in the photodetection devices. Specifically, the impact of screw dislocations on the performance of GaN based metal-semiconductor-metal ultraviolet photodetector is investigated. The experiments reveal that reducing screw dislocations had a strong impact on dark current (similar to 3x decrement) of the devices as well as on the photogenerated current (similar to 20x enhancement) upon illumination (ultraviolet, 325 nm). The responsivity of the photodetection device has been increased from 85.05 mA/W to 130.17 mA/W with decreasing dislocation density. Because, higher dislocations created leakage paths that develop trap states which enhances the possibility of recombination process of photo-generated electron-hole pairs leading to lower charge collection. Further, the external quantum efficiency increases from 32.51% to 49.76% by reducing dislocation density. The work in this study proposes that reduction of defects/dislocations will be an effective approach to enrich the III-nitride semiconductor system for advancement in optoelectronic devices.

Automated summary

The reduction of screw dislocations has a significant impact on improving the performance of photodetection devices, including decreasing dark current and enhancing photogenerated current. Additionally, reducing dislocation density can increase the responsivity and external quantum efficiency of photodetection devices.