UV Photodetector Based on Graphene − ZnO Nanowire Hybrid : 1 Fabrication , Photoresponse and Photoluminescence Studies

Herein, we demonstrate a graphene based efficient UV photodetector by using vertically aligned ZnO 8 NWs on chemical vapor deposited graphene with and without a ZnO buffer layer. The effect of rapid 9 thermal annealing (RTA) on grapheneZnO thin film hybrid prior to the growth of ZnO NWs by physical 10 vapor deposition technique is investigated from the μRaman spectroscopy and high resolution 11 transmission electron microscopy. The change in the relative intensities of 2D and D band Raman modes 12 and a red shift in 2D band (~ 13 cm) after RTA treatment in ZnO coated graphene substrate reveals the 13 strong interaction between graphene and ZnO hexagonal lattice, covalent sp carbon lattice. The vertical 14 ZnO NWs with high aspect ratio on the grapheneZnO thin film hybrid exhibit enhanced UV absorption, 15 strong UV and visible photoluminescence and improved UV photoresponse. There is a 6 fold 16 enhancement in the photocurrent in ZnO NWs grown on graphene as compared to the ZnO NWs grown 17 on bare ZnO seed layer. The improved performance of these graphene based 2D1D integrated hybrid ZnO 18 nanostructures is an important step towards the fabrication of hybrid photodetectors and phototransistors 19 with enhanced UV response. 20