Ultraviolet Photonic Response of AlGaN/GaN High Electron Mobility Transistor-Based Sensor with Hydrothermal ZnO Nanostructures

We present the first active high-performance ultraviolet (UV) sensor based on aluminum gallium nitride (AlGaN)/GaN high electron mobility transistors (HEMTs) with zinc oxide (ZnO) nanorods (NRs) selectively grown on the gate area by hydrothermal method. Faster response and recovery times (similar to 10 and similar to 190 ms) are obtained from the NR-gated sensors than those (similar to 270 and similar to 660 ms) of the seed-layer-gated devices by the periodic switching of the UV light under the same measurement conditions. This response speed is much superior to those of other ZnO nanostructure-based passive sensors, which exhibit much slower response times of several tens or hundreds of seconds. The NR-gated HEMT sensors show a very high responsivity of 1.1x10(5) A/W at a source optical power of 100 W and a wavelength of 300 nm, which is about one order higher than the best responsivity of a ZnO nanowire-based sensor reported to date. This improvement in responsivity and sensing speed is owing to the reduction in dimensionality with the ultra-high surface-to-volume ratio of the three-dimensional ZnO NR sensing structure and high performance characteristics of the AlGaN/GaN HEMTs.