Enhanced Photodetection by Glancing Angle Deposited Vertically Aligned TiO2Nanowires

The TiO2thin film (TF) and nanowires (NWs) have been synthesized on Si substrate from pellets of pressed and sintered TiO2powder using e-beam evaporation. The glancing angle deposition technique is adopted for the growth of TiO2NWs. Field emission gun-scanning electron microscope analysis manifests the growth of vertically aligned NWs of length ~362 nm and diameters ranging from ~50 to ~290 nm. Energy dispersive X-ray analysis of NW sample shows the presence of Titanium (Ti), Oxygen (O2) and Silicon (Si). The transmission electron microscope analysis also confirms successful growth of NWs and the selected area diffraction pattern shows the bright spot patterns from the crystals. X-ray diffraction of TF and NWs deposited at ambient temperature demonstrate multiple peaks from the anatase phase of TiO2which supports the selective area diffraction pattern result. Under light exposure, the current densities for TF and NW device are ~5.11 and ~10.03 μA/cm2, respectively, at +6.5 V. A maximum photosensitivity of ~10 times is recorded for the NW device at -6.5 V. An excellent response with rise and fall times of ~0.16 and ~0.17 s respectively is observed during switching on and off of white light at +8 V for the NW device, which confirms promising photodetection applications.