Plasmonic Photoresistor Based on Interconnected Metal‐Semiconductor Grating

Abstract

Metal‐semiconductor nanostructures in various configurations are extensively used in photodetection, photocatalysis, and photovoltaics. For photodetection purposes, the working principle is straightforward; on illumination, generated charge carriers in excess lead to a decrease in resistance. Notably, using an interconnected metal‐semiconductor grating, it is observed and now reported an opposite response, an increase in the resistance. Such photoresistors are fabricated through wrinkle structuring and oblique angle material deposition methods. It is found that the controlled wrinkling leads to large‐area 1D periodic structures with coexisting cracking perpendicular to the grating direction—such cracks are used as connections between the two‐point contact measurement through the associated gold layer deposition. An enhanced current reduction is further observed on photoexcitation for an additional deposition of an amorphous titania layer. Subsequently, a discussion on the mechanisms and interaction between hot electron injection, charge carrier recombination, and thermalization is presented. Supported by numerical modeling, the angle‐resolved plasmonic modes with the photoresistance can be correlated. The ease of layered deposition of the materials allows one to extend the studies on cavity‐based structures with sandwiched titania layers as hotspots. This simple, scalable, and robust fabrication method thus promises an efficient routeway toward photosensor development in which plasmon‐mediated hot electrons play a crucial role.

Engineering Plasmonic Hybridization toward Advanced Optical Sensors

“…By applying high oblique angled depositions (OAD), one can also produce periodic metallic structures using the shadowing effect from the template structures. [ 273,274 ] The separate second metallic layer formed within the trenches/ holes complements the resist template for proceeding with lift‐off processes using the normal deposition. By dissolution of the in‐between resist layer, one can remove both the resist and the top sacrificial layer to produce the complementary metallic array.…”

Structural and optical properties of highly Ag-doped TiO2 thin films prepared by flash thermal evaporation

“…Many studies have demonstrated that the photocatalytic properties of TiO2, when containing metal nanoparticles (NPs), are notably improved across both the ultraviolet (UV) and visible spectra [19]. This enhancement is attributed to charge transfer processes occurring at the interfaces between oxide and metal nanoparticles (NPs) in systems featuring both periodically arranged plasmonic nanostructures and randomly distributed plasmon nanoparticles embedded within an oxide matrix [23][24][25][26][27][28]. Ag nanoparticles, owing to their surface plasmon resonance SPR, exhibit remarkable optical properties.…”