Unconventional Enhancement of UV Photodetection in Surface-Passivated TiO<sub>2</sub> Thin Film Photodetectors
Nabeel M.S. Kaawash, Devidas I. Halge, Vijaykiran N. Narwade, Pooja M. Khanzode, Mohammed Y. H. Thabit, Asma Begum, Sohel J. Shaikh, Jagdish W. Dadge, Prashant S. Alegaonkar, Kashinath A. Bogle
Abstract
Extensive research has been conducted on UV photodetectors employing metal oxide thin films, which exhibit numerous advantageous qualities, notably encompassing current stability and a substantial light-to-dark current ratio. Nevertheless, these devices encounter challenges related to elevated dark current levels and sluggish response times due to oxygen vacancy-related surface defects. In this study, we report an unconventional enhancement in the UV photodetection properties of surface-passivated TiO 2 thin film-based photodetector devices operating at a 30 V applied bias. The responsivity significantly increases from 1.6 to 53 A/W, while the detectivity rises from 1.6 × 10 14 to 2.88 × 10 15 Jones. Sensitivity and external quantum efficiency also exhibit substantial improvements, along with an unexpected trend of responsivity increasing with the UV light intensity. The introduced surface passivating layer plays a crucial role in reducing surface trap states and dark current, leading to an anomalous enhancement in carrier concentration and photocurrent with increasing incident UV light. This results in speedy response times with a rise time of 13 ms and a decay time of 8 ms. Overall, the study suggests that incorporating a surface passivating layer onto TiO 2 holds promise for highly efficient UV photodetectors.