A synergetic enhancement strategy of light utilization and carrier transfer for UV photodetection associated with artificial resonance nano-cavities

Low-dimensional wide bandgap semiconductors demonstrate great potential in the large-scale fabrication of new-generation ultraviolet (UV) photodetectors (PDs) with an excellent combination of the integration level and easily tunable response spectra. However, the thickness dependence on the defect density and light absorption negatively affects the carrier photogeneration and transportation in photoactive layers, hindering the simultaneous realization of high sensitivity and low noise during detection. Herein, artificial resonance nano-cavities of 0D/2D ZnO quantum dot (QD)/MXene nanosheet (NS) composite thin films on a distributed Bragg reflector (DBR) are proposed toward high-performance UV photodetection. The uniformly distributed MXene NSs can concentrate incident photons within the composite thin films via boosted near-surface electromagnetic fields, and the extraction and transfer processes of photoinduced carriers are subsequently accelerated as experimentally and theoretically evidenced. The spatial light coupling between MXene NSs and the DBR with well-balanced periods of two dielectric layers further compensates for the unfavorable light-matter interaction within the 0D/2D composite thin films induced by the noticeable light transmission, and the comprehensive enhancement in the whole photocurrent generation procedure instantaneously endows the device with outstanding EQE (489.1%) and D* (1.7 x 1013 jones), which opens a practicable route for the fabrication of UV photodetectors with exceptional optoelectronic response and long-term stability. Light confinement can be significantly boosted with the artificial resonance nano-cavities between MXene nanosheets and distributed Bragg reflectors. The carrier separation and transfer processes are simultaneously enhanced by the construction of the electron pathway with those nanosheets.