Effect of annealing on SiOx-TiO2 axial heterostructure nanowires and improved photodetection

Glancing angle deposition technique has been used to synthesize the axial heterostructure SiOx-TiO2 nanowires (NWs) on the Si substrate. The field emission gun scanning electron microscope image shows the formation of perpendicular NWs on Si substrate. A typical transmission electron microscope image confirms the heterostructure NW which consists of SiOx of length ∼130 nm and TiO2 of length ∼170 nm. The amorphous NWs transformed to polycrystalline nature after annealing. The trap assisted radiative recombination process is absent for the annealed NWs. An averagely 1.1 fold enhanced photoabsorption was exhibited by the annealed NWs in the 200–350 nm region and 1.5 fold in the 500–850 nm region. The leakage current (2.6 × 10−8 A/cm2 at −0.5 V) significantly reduced for annealed NWs device. A maximum 1.4 × 103 times enlarged photodetection has been observed for annealed device.