Oblique Angle Deposition of Slanted TiO₂ Columnar for UV Photodetector Application

With the advancement of optoelectronic technology, a new evaluation of photodetectors' (PDs') performance is necessary for next-generation sensing applications. This study uses the e-beam evaporation approach to produce slanted titanium dioxide columnar (TiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>-COL) on the Si substrate, with a constant deposition angle of ∼ 61°. The morphology, structural, and optical properties of the fabricated TiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>-COL samples were examined. Successful growth of the slanted TiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>-COL structure is demonstrated by field emission scanning electron microscopy (FESEM). Furthermore, XRD analyses reveal that TiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>-COL has an amorphous nature. Optical characterization reveals that the fabricated sample exhibits high absorption intensity in the UV region, for demonstrating a potential UV photodetector application. The TiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>-COL based PD that was deposited obliquely displayed I-V curves that demonstrated a distinct photovoltaic mode and an extremely low dark current of a few nanoamperes. Moreover, at ∼ 320 nm, the device exhibits a self-powered UV light response with a responsivity value of around ∼ 1.3 mA/W. In addition, this TiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>-COL based photodetector device demonstrates a remarkable detectivity and noise-equivalent-power (NEP) and rise time/fall time of ∼ 4.63 × 1010 Jones, ∼ 6.06 × 10-11 W and ∼ 0.305/0.184 sec, respectively, at - 0.1 V. Therefore, this novel idea of a slanted TiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>-COL structure promotes effective light management and offers a reliable route for creating Low-powered UV PDs.