Phonon assisted electron emission from quasi-freestanding bilayer epitaxial graphene microstructures

Daniel Lewis; Brendan Jordan; Michael Pedowitz; Daniel J Pennachio; Jenifer R Hajzus; Rachael Myers-Ward; Kevin M Daniels

doi:10.1088/1361-6528/ac7653

Phonon assisted electron emission from quasi-freestanding bilayer epitaxial graphene microstructures

Nanotechnology. 2022 Jun 24;33(37). doi: 10.1088/1361-6528/ac7653.

Authors

Daniel Lewis^{1

2}, Brendan Jordan^{1

2}, Michael Pedowitz^{1

2}, Daniel J Pennachio³, Jenifer R Hajzus³, Rachael Myers-Ward³, Kevin M Daniels^{1

2}

Affiliations

¹ Department of Electrical and Computer Engineering, University of Maryland, College Park, MD 20742, United States of America.
² Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20742, United States of America.
³ US Naval Research Laboratory, Washington, DC 23075, United States of America.

PMID: 35671745
DOI: 10.1088/1361-6528/ac7653

Abstract

Electron emission from quasi-freestanding bilayer epitaxial graphene (QFEG) on a silicon carbide substrate is reported, demonstrating emission currents as high as 8.5μA, at ∼200 °C, under 0.3 Torr vacuum. Given the significantly low turn-on temperature of these QFEG devices, ∼150°C, the electron emission is explained by phonon-assisted electron emission, where the acoustic and optical phonons of QFEG causes carrier acceleration and emission. Devices of differing dimensions and shapes are fabricated via a simple and scalable fabrication procedure and tested. Variations in device morphology increase the density of dangling bonds, which can act as electron emission sites. Devices exhibit emission enhancement at increased temperatures, attributed to greater phonon densities. Devices exhibit emission under various test conditions, and a superior design and operating methodology are identified.

Keywords: bilayer graphene; electron emission; epitaxial graphene; microstructures; phonon assisted; quasi-freestanding.