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.