Ultrafast UV AlGaN Metal–Semiconductor–Metal Photodetector With a Response Time Below 25 ps

Aluminum-gallium-nitride photodetectors were successfully fabricated with micrometer-scale metal–semiconductor–metal structures and tested with ultrafast, UV laser pulses. The measurements were done with single-shot oscilloscopes. Pulse-broadening effects caused by the measurement system were systematically evaluated and reduced to resolve the intrinsic response time of the detector. The best-performing devices showed a response time of below 25 ps and dark currents below 20 pA. The devices showed linear response with the bias voltage and the laser energy.