Field Enhancement in Plasmonic Nanostructures

TL;DR

This paper demonstrates how plasmonic resonant surfaces can significantly enhance electric fields at metallic interfaces, enabling efficient charge carrier generation for vacuum devices with reduced power requirements.

Contribution

It introduces a simple planar plasmonic structure that models and measures field enhancement, providing insights into electron emission mechanisms and potential vacuum device applications.

Findings

Optical field enhancement of 1000 times at the metal interface.

Strong agreement between experimental measurements and analytical models.

Observation of significant photocurrents with combined optical and DC excitation.

Abstract

Efficient generation of charge carriers from a metallic surface is a critical challenge in a wide variety of applications including vacuum microelectronics and photo-electrochemical devices. Replacing semiconductors with vacuum/gas as the medium of electron transport offers superior speed, power, and robustness to radiation and temperature. We propose a metallic resonant surface combining optical and electrical excitations of electrons and significantly reducing powers required using plasmon-induced enhancement of confined electric field. The properties of the device are modeled using the exact solution of the time-dependent Schr\"odinger equation at the barrier. Measurement results exhibit strong agreement with an analytical solution, and allow us to extract the field enhancement factor at the surface. Significant photocurrents are observed using combination of W/cm^2 optical power and 10 volts DC excitation on the surface. The model suggests optical field enhancement of 3 orders of magnitude at the metal interface due to plasmonic resonance. This simple planar structure provides valuable evidence on the electron emission mechanisms involved and it can be used for implementation of semiconductor compatible vacuum devices.