Laser Science and Technology branch, Department of Applied Sciences, University of Technology -Iraq
Graphene-ZnO nanohybrid thin films were prepared by the spray pyrolysis technique at 350 °C with graphene nanoplate concentrations of 0.1, 0.2, 0.3, 0.4, and 0.5 wt.% deposited on quartz and silicon substrates. The structural and electrical properties have been investigated. XRD results show that the films have a hexagonal wurtzite polycrystalline structure. AFM images showed how the grains are distributed and arranged on the surfaces and illustrated the effect of graphene concentration on the properties of the film by measuring the roughness and grain size. FESEM showed that the surface of the film without graphene is covered with high-packing hexagonal grains with a narrow grain size distribution. At a higher graphene content of 0.5 wt.%, graphene nanoplates distributed within the ZnO matrix were observed. The current-voltage characteristics of the heterojunction show a typical rectification behavior. The photocurrent under illumination measurement has increased gradually with increasing light intensity and graphene concentration. The capacitance-voltage characteristics show that the built-in potential barrier (Vbi) value ranges from 0.65 V for ZnO/Si to 0.3 V for G-ZnO/Si with 0.5 graphene. The spectral responsivity of the photodetector was enhanced for the G-ZnO hybrid at 0.5 graphene.