Plasmon-induced Ag decorated CeO2 nanorod array for photodetector application

Abstract

In this work, glancing angle deposition (GLAD) has been used to grow Ag decorated CeO2 nanorod (NR) array on n-type Si substrate. The length of the NRs obtained was ∼235 nm and the size of the Ag NPs varied from 13 to 41 nm. The polycrystalline and crystalline nature of CeO2 and Ag respectively was revealed via selected area electron diffraction (SAED) analysis as well as x-ray diffraction (XRD) pattern. Optical absorption measurement depicts a distinct broad peak around 413 nm that is ascribed to the localized surface plasmon resonance (LSPR) effect of Ag NPs. The Ag decorated CeO2 NR device exhibited a turn on voltage at ∼3.2 V under dark, which then reduced to ∼1.3 V under 35 min illumination along with the increase in device current from 2.8 to 24.5 μA cm−2 (4 V) on continuous exposure to light. Under white light illumination, a responsivity of 4.51 A W−1 was obtained at 370 nm along with the detectivity and noise equivalent power (NEP) values of 4.15 × 1012 jones and 0.01 pW respectively. Additionally, a fast response characteristic with rise and fall times of 74 ms and 42 ms respectively was demonstrated. Thus, these findings manifest the underlying LSPR mechanism at work in Ag/CeO2 heterojunction and reveal its high potential in UV photodetector application.