Al nanoparticles decorated Er:TiO2 thin film based plasmonic photodetector

Abstract

Aluminum (Al) nanoparticles (NPs) patterned Erbium-doped Titanium dioxide (Er:TiO2) thin films (TFs) were synthesized by the combination of sol-gel and glancing angle deposition (GLAD) technique inside the thermal evaporation system. Effects of Al NPs on electrical and optical properties of the Er:TiO2 TF were experimented and systematically analyzed. Size of NPs was estimated from the field emission scanning electron microscopy (FESEM) image. Diameter of the maximum number of Al NPs was determined to be ∼13 nm. The presence of Al was confirmed from the energy dispersive X-ray (EDX) spectra. The optical absorption at around 315 nm revealed the plasmonic resonance of Al NPs. The Au/Er:TiO2/Al NPs/Er:TiO2/p-Si Schottky contact-based plasmonic photodetector (PD) was fabricated, which showed excellent photosensitivity under both forward and reverse bias conditions. The responsivity was calculated at an applied voltage of 1 V, which exhibited a high response in the UV region with peak responsivity at 330 nm and 380 nm. The device showed fast switching behaviors under the illumination of 350 nm with a rise time of ∼0.55 s and fall time of ∼0.13 s. A simple theoretical approach was adopted to evaluate some important parameters of the plasmonic device like photoconductive gain, transit time, and mobility of electrons. Detectivity (1.13 × 1012 Jones) and noise equivalent power (NEP) (2.46 × 10−14 W) at 330 nm indicate the suitability of the device as a sensitive UV PD. Hence, the embedded plasmonic Al NPs on Er:TiO2 TF-based devices can commercially emerge as an efficient and cost-effective UV photodetector.