Flake-like ZnO nanostructures density for improved absorption using electrochemical deposition in UV detection

Ultra violet photodetector based on flake-like ZnO with different flakes density were electrochemically deposited on silicon Si (1 1 1) substrate were fabricated. The deposition time greatly affected the shape, density and size of the flake, thereby altering its optical properties. The structural and optical properties of the fabricated nanostructures revealed ZnO structures with single crystalline hexagonal wurtzite containing two photoluminescence spectrum peaks at a near-band-edge emission in the ultraviolet region and a broad deep-level emission around the green emission. These peaks were affected by the period of deposition. The crystallinity of materials and the defects in the crystal structure were studied through Raman spectroscopy. Current voltage results showed that the flakes density greatly affected the ultra violet detection. Our results showed that photoresponse properties of the photodetectors strongly depend on the flakes density. The sharper flakes with high density exhibited enhanced UV detection performance, high sensitivity and shortened rise times compared to lower ones. We showed that photodetectors based on sharp, highly dense ZnO nanoflakes have a faster response than ones based on larger and lower density of ZnO nanoflakes.