The improvement of GaN p-i-n UV sensor by 8-pair AlGaN/GaN superlattices structure

Abstract

GaN with pairs of AlGaN/GaN superlattices (SLs) structure for p-i-n UV photo detector are fabricated on sapphire by metal organic chemical vapor deposition (MOCVD). For 8-pair AlGaN/GaN SLs not only eliminates cracking through this strain management, but it also significantly decreases the threading dislocation density by acting itself as an effective dislocation filter. The related structure has exhibited excellent film qualities such as enhanced crystallinity, lower specific contact resistance, lower etching pit density or mean roughness in the film. GaN p-i-n diode fabricated with 8-pair SLs, the dark current of device is reduced by two orders of magnitude than that without SLs structure at reverse bias of −3 V. Moreover, the peak UV responsivity is 0.12 A/W, which is higher than that without SLs is 0.07 A/W at 360 nm. The rejecting ratio is also by two orders of magnitude higher than that without SLs structure.