Low-Voltage Electron Emission by Graphene-hBN-graphene Heterostructure

TL;DR

This paper demonstrates a novel low-voltage, planar electron source using graphene-hBN-graphene heterostructures, achieving significant emission current at very low voltages suitable for next-generation electron devices.

Contribution

The study introduces a low-voltage planar electron source based on 2D heterostructures with record low extraction voltage and high emission current density.

Findings

Achieved electron emission at 20V with an external electric field of 4×10^4 V/m.

Steady emission of over 1nA for several hours from a 59.29 μm² device.

Maximum emission current density of 7 mA/cm².

Abstract

Scanning Electron Microscopes (SEM) with low energy electron sources (accelerating voltage of less than 1000V) have important application requirements in many application scenarios. Tunneling junction can potentially achieve low-voltage and planar-type electron sources with good emission current density. However, further lower the extracting voltage while ensure the emission current density remains challenging. In this paper, we report a low-voltage planar-type electron source based on graphene-hBN-graphene heterostructures (GBGH) under a really low out-plane extracting voltage. The external electric field strength applied to the electron sources is only 4 times 10^4V/m and the accelerating voltage as low as 20V is realized. Steady electron emission of over 1nA and operating duration of several hours is observed from the GBGH with size of 59.29um^2 in our experiments, and thus the maximum emission current density reaches 7mA/cm^2. Great electrical contacts, extremely low thickness, and excellent layer properties of two-dimensional (2D) materials lead to easy-fabrication and miniature on-chip electron sources, which would significantly contribute to the development of next-generation free electron devices.