Ultra-violet photodetection enhancement based on ZnO–graphene composites fabricated by sonochemical method

The mono-and/or few-layers graphene oxide (GO) was synthesized by modified Hummers method. The (GO) incorporated ZnO composites were fabricated by sonochemical method. The X-ray diffraction (XRD) patterns of 2.5 wt% GO incorporated composite showed co-existence of GO and ZnO-wurtzite peaks in composite sample. Based on the morphological evolution of ZnO from scanning electron microscopy images and XRD patterns, the negatively charged GO sheets contributed in ZnO crystals nucleation and growth in sonochemical synthesize. The elimination of functional group bands in Fourier transform infrared spectra for composite samples implied an effective thermally reduction of GO. The results of ultra-violet photodetection measurements shown that the composite photodetectors not only possessed a desirable sensitivity, but also the response and recovery time were reduced to about one-third of pure ZnO nanopowder. The improved ultra-violet detection of composite samples was ascribed to the existence of highly conductive rGO frameworks which inhibit the photogenerated carriers from recombination and conducted them between electrodes.