Investigation of structural, optical and electrical properties of TiO2 thin film-nanowire-based device for photodetector application

Abstract

In this work, titanium dioxide (TiO2) has been used for fabricating the thin film (TF) and perpendicular nanowire (NW) arrays using the glancing angle deposition (GLAD) technique on p-type silicon (Si) substrates. X-ray diffraction (XRD) plots confirmed the presence of anatase and rutile phases in both structures. Transmission electron microscopy (TEM) indicates a TF layer of ∼150 nm and NW of ∼280 nm in length. The selected area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDS) present the amorphous morphology and elemental composition. Strikingly, a 1.25 times boost in UV–Vis absorption was observed in TiO2 NW/TiO2 TF as compared to TiO2 TF samples. Bandgaps of the fabricated TiO2 TF and TiO2 NW/TiO2 TF were also determined to be 3.5 eV and 3.59 eV, respectively. The frequency-dependent responses of the TiO2 TF and TiO2 NW/TiO2 TF devices were investigated by capacitance-voltage (C–V) measurements. Moreover, the current density-voltage (J-V) characteristics exhibit an average 100 times increment in the current conduction of TiO2 NW/TiO2 TF as compared to the TiO2 TF device, which can be an excellent candidate in photodetection.