Highly sensitive and self powered ultraviolet photo detector based on ZnO nanorods coated with TiO2

Nanorods (NRs) of crystalline ZnO coated with thin layers TiO$_2$(ZnO@TiO$_2$) were fabricated the help spin coating technique followed by hydrothermal method. Scanning electron microscopy (SEM) and X-ray diffraction analysis confirms morphology structural stability as-prepared NRs. The optical band gaps NRs estimated, a clear blue shift toward UV region has been detected. When light falls on device (i.e., in "ON" state), significant increase photocurrent (I$_{UV}$) at zero voltage supply was observed from 6 $\mu$A to 17 while "OFF" state, dark current (I$_{dark}$), increases 0.08 0.6 ZnO@TiO$_2$ as compared bare respectively. Responsivity detectivity TiO$_2$ based found maximum unlike Enhanced achieved growth is 250 for which it 35 10 V under ultraviolet irradiation (illumination intensity 1 mW/cm$^2$). Furthermore, theoretical calculations have performed using first-principles density-functional theory understand effects heterostructure electronic properties ZnO.