Influence of trap level on an Al0.6Ga0.4N/Al0.5Ga0.5N metal—semiconductor—metal UV photodetector

Abstract

Abstract The irradiation intensity and temperature characteristics of each response speed sample are measured to clarify the high photosensitivity mechanism in an Al0.6Ga0.4N/Al0.5Ga0.5N metal–semiconductor–metal photodetector. A tradeoff relation could be observed between the photosensitivity and response speed when the dependence of the saturated photocurrent on the irradiation intensity was investigated by changing the irradiation intensity from 1 nW cm−2 to 45 μW cm−2. The rise time of the photocurrent after exposure to ultraviolet light was measured to determine the trap level density that was estimated to be ca. 1012 cm−2. Further, the decay time constant was obtained by investigating the dependence of the photocurrent decay time on temperature (25 °C–180 °C). By analyzing the Arrhenius plot of the decay time constant versus inverse temperature, trap level depths of 0.23 and 0.67 eV were obtained. Thus, the high photosensitivity in the Al0.6Ga0.4N/Al0.5Ga0.5N photodetector can be attributed to the carriers trapped in deep-level traps.