The fabrication of a superior-performance ultraviolet (UV) photodetector utilizing graphene quantum dots (GQDs) as a sensitization agent on a ZnO-nanorod/GaN-nanotower heterostructure has been realized. GQD sensitization displays substantial impact on the electrical as well as the optical performance of a heterojunction UV photodetector. The GQD sensitization stimulates charge carriers in both ZnO and GaN and allows energy band alignment, which is realized by a spontaneous time-correlated transient response. The fabricated device demonstrates an excellent responsivity of 3.2 × 10 3 A/W at −6 V and displays an enhancement of ∼265% compared to its bare counterpart. In addition, the fabricated heterostructure UV photodetector exhibits a very high external quantum efficiency of 1.2 × 10 6 %, better switching speed, and signal detection capability as low as ∼50 fW.

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 (≈nA) with a very high responsivity (132 mA W−1) and detectivity (2.4 × 1010 Jones). A remarkably high light‐to‐dark current ratio of ≈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 photodetectors. 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.

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