A Highly Responsive Self-Driven UV Photodetector Using GaN Nanoflowers

The rising demand for optoelectronic devices to be operable in adverse environments necessitates the sensing of ultraviolet (UV) radiation. Here, a self-driven, highly sensitive, fast responding GaN nanoflower based UV photodetector is reported. By developing unique structures, the light absorption increases efficiently and a maximum responsivity of 10.5 A W-1 is achieved at 1 V bias. The reported responsivity is the highest among the GaN UV photodetectors on Si substrates and commercially available Si-based UV photodetectors. Under self-driven condition, the photodetector exhibits very low dark current (approximate to nA) with a very high responsivity (132 mA W-1) and detectivity (2.4 x 10(10) Jones). A remarkably high light-to-dark current ratio of approximate to 260 signifies extremely high photodetection gain compared to planar GaN-based photodetectors. The self-driven and biased photodetector device yields highly stable rise and decay time response. A model based on band theory elucidates the origin of self-driven photodetectors. Implementation of the innovative growth design structures assures an exceptionally high sensitivity toward UV signal, which is capable of substituting the existing technology of UV photo-detectors. High responsivity and detectivity from devices based on the GaN nanoflower-like structure with the advantage of high surface/volume ratio can have numerous applications in fabrication of nanoscale optoelectronic high performance devices such as self-driven UV photodetectors.