Electric imaging and dynamics of photo-charged graphene edge

TL;DR

This paper uses scanning nitrogen-vacancy microscopy to visualize and analyze the electric field distribution near graphene edges under photo-charging, revealing nanoscale effects and charge transfer mechanisms relevant for graphene-based nanoelectronics.

Contribution

It introduces a novel real-space imaging method for electric fields at graphene edges and develops a theory based on photo-thermionic effects to explain charge transfer phenomena.

Findings

Nanoscale electric field maps of photo-charged graphene edges were obtained.

Charge transfer from graphene to diamond surface is explained by photo-thermionic effect.

Real-time imaging captured electron emission and recombination processes.

Abstract

The one-dimensional side gate based on graphene edges shows a significant capability of reducing the channel length of field-effect transistors, further increasing the integration density of semiconductor devices. The nano-scale electric field distribution near the edge provides the physical limit of the effective channel length, however, its imaging under ambient conditions still lacks, which is a critical aspect for the practical deployment of semiconductor devices. Here, we used scanning nitrogen-vacancy microscopy to investigate the electric field distribution near edges of a single-layer-graphene. Real-space scanning maps of photo-charged floating graphene flakes were acquired with a spatial resolution of $\sim$ 10 nm, and the electric edge effect was quantitatively studied by analyzing the NV spin energy level shifts due to the electric Stark effect. Since the graphene flakes are isolated from external electric sources, we brought out a theory based on photo-thermionic effect to explain the charge transfer from graphene to oxygen-terminated diamond probe with a disordered distribution of charge traps. Real-time tracing of electric fields detected the photo-thermionic emission process and the recombination process of the emitted electrons. This study provides a new perspective for graphene-based one-dimensional gates and opto-electronics with nanoscale real-space imaging, and moreover, offers a novel method to tune the chemical environment of diamond surfaces based on optical charge transfer.