Al 0.40 in 0.02 Ga 0.58 N based metal-semiconductor-metal photodiodes for ultraviolet detection

High crystalline quality Al_0.40 In_0.02Ga_0.58N film has been achieved on GaN buffer by metalorganic vapor phase epitaxy (MOVPE). The metal-semiconductor-metal (MSM) structured visible blind photodetector was fabricated based on the Al_0.40 In_0.02Ga_0.58N film. The current-voltage measurement indicated an obvious Schottky behavior, the barrier height was calculated to be 0.98 e V. With an applied bias of 10 V, the photodetector showed a peak responsivity of 0.065 A/W at 295 nm with a cutoff wavelength at 310 nm. Furthermore, the ultraviolet-visible rejection ratio (R295 nm/R450 nm) was more than two orders of magnitude at 10 V bias. It was also found another response peak at 360 nm corresponding to the band gap of GaN, Which proved our photodetector can be used for dual band detection in ultraviolet region. In addition, it was also found that the slower increased of the responsivity when the |bias| was above 3V was attributed to radiative and Auger recombination.