Optoelectronic Materials And Devices Based On ZnO Quantum Dots

ZnO quantum dots comprise the merits of wide direct bandgap, high radiationresistance, environmentally friendly, high electron saturation velocity, etc. from ZnOand convenient integration, tunable bandgap, etc. from quantum dots. Hence ZnOquantum dots have been regarded as a promising candidate for ultravioletphotodetection. However, the current responsivity and detectivity of ZnO-basedultraviolet photodetectors is still below expectation. To solve this problem, we havecomposited ZnO quantum dots with carbon nanodots, and the optical andphotodetection properties of the hybrid films have been studied, and the main resultsof our research are listed below:1A MSM type ultraviolet photodetector has been fabricated from the ZnOquantum dots and carbon nanodots composite material, it is found that theintroduction of carbon nanodots can increase the performance of thephotodetectors greatly, which showed obvious response to a very low weakultraviolet signal (12nW/cm2). The detectivity and noise equivalent powerof the photodetector can reach3.1×1017cmHz1/2/W and7.8×10-20W,respectively, both of which are the best values ever reported for ZnO-basedphotodetectors.2The optical character of the ZnO/C composite material has been studied, itis found that the fluorescence of carbon nanodots was quenched while that of ZnO quantum dots was enhanced. Meanwhile, the lifetime of carbonnanodots was constant while that of ZnO quantum dots decreased from1297ns to20ns. The enhancement in the photoluminescence of the ZnOQDs can be attributed to be resulted from the surface plasmons of thecarbon nanodots.