Enhancement of Broad Light Detection Based on Annealed Al-NPs Assisted TiO2-NWs Deposited on p-Si by GLAD Technique

In this paper, broad band light detection properties of annealed vertically aligned TiO2 Nanowires (NWs) and Al Nanoparticles assisted TiO2 NWs (Al-NPs-TiO2-NWs) fabricated on Si substrates using indigenous glancing angle deposition system are investigated. The XRD spectrum manifests that the grain size of polycrystalline anatase TiO2 increases after annealing and also confirms the presence of small Al nanocrystals in the sample supporting the TEM result. The optical absorption spectra analysis of both as-deposited and annealed Al-NPs-TiO2-NWs reveals that the incorporation of Al-NPs in TiO2-NWs enhances the photon absorption in UV and visible region as compared to annealed TiO2-NWs. The I-V characteristics of Al/TiO2-NWs/p-Si and Al/Al-NPs-TiO2-NWs/p-Si photodetectors show the rectifying behavior due to p-n junction formation at the interface of TiO2 and p-Si. It is interesting to observe that Al/Al-NPs-TiO2-NWs/p-Si based device gives better photosensitivity as compared to Al/TiO2-NWs/p-Si under visible light illumination at reverse bias condition which may be due to SPR effect of Al NPs. This result confirms that the growth of Al-NPs-TiO2-NWs using this simple technique may be applicable for broad band light detection for different optoelectronic applications.