The improvements of GaN p-i-n UV sensor on 1° off-axis sapphire substrate

A thin gallium nitride (GaN) layer epitaxially grown on misorientation angles of a-plane 1° off-axis sapphire substrate by metal organic chemical vapor deposition (MOCVD) has exhibited excellent film qualities such as enhanced crystallinity, lower defect levels, and less etching pit density. Accordingly, the GaN p-i-n photodetector fabricated on 1° off-axis sapphire substrate the dark current density decreased from 2.4 × 10−9 A/cm2 to 1.82 × 10−11 A/cm2 at −3 V, the responsivity increased from 0.06 A/W to 0.105 A/W at 360 nm with no applied bias; the ultraviolet/visible (UV/vis) rejection ratio increased from 2.32 × 103 to 2.48 × 104 (comparing wavelength 360-450 nm). A superior device performance could be achieved, as device fabricated on 1° off-axis sapphire substrate.