Impact of crystallinity towards the performance of semi-polar (11–22) GaN UV photodetector

Abstract Crystal engineered semi-polar (11–22) GaN-based UV photodetectors have been fabricated which exhibit two dissimilar photo-responses depending on the crystal quality. The higher crystal quality evaluated via x-ray rocking curve (XRC) exhibited remarkable narrow full width half maximum (FWHM) along [-1–123] and [1–100] of 0.11° (396 arcsec) and 0.28° (1008 arcsec), respectively. Integration of the high crystalline structure with the metal–semiconductor-metal type photodetector resulted in notably lower dark current of 4.6μA. The responsivity value is significantly enhanced from 117 mA/W to 325 mA/W with higher crystalline epilayer. The photo-response of the detector made with the enhanced crystal epilayer is measured to be as low as 170 ms with a recovery time of 241 ms by which is the fastest switching time ever reported in semi-polar (11–22) GaN metal–semiconductor-metal UV photodetector.