Improving plasmonic photodetector based on ITO/TiO2/Ag configuration and roughened interface

Abstract

In this work, plasmonic photodetector based on ITO/TiO2/Ag grating configuration specially with nano-scale roughened interface is proposed to achieve high photoresponsivity, in which hot-electron are effectively excited by taking advantages of the narrow distribution of excitation energy in Ag and the high density of states in TiO2 conduction band. Simultaneously, a roughened structure is introduced at Ag/TiO2 interface to alleviate the momentum mismatch of hot-electron. The influences of the grating structures on incident light absorption and hot-electron excitation are simulated by using finite-difference time-domain method. The thicknesses of both metallic Ag and spacer layers modulate the absorption characteristics, and the introduction of the nano-scale roughened interface does not have effect obviously on the absorptivity and response wavelength. The present work provides a valuable guidance in the fields of interface design and structure optimization of high-efficiency plasmonic photodetectors.