Title: Imaging electron motion in graphene

Abstract

A cooled scanning probe microscope (SPM) is an ideal tool to image electronic motion in graphene: the SPM tip acts as a scanning gate, which interacts with the electron gas below. We introduce the technique using our group's previous work on imaging electron flow from a quantum point contact in a GaAs 2DEG and tuning an InAs quantum dot in an InAs/InP nanowire. Carriers in graphene have very different characteristics: electrons and holes travel at a constant speed with no bandgap, and they pass through potential barriers via Klein tunneling. In this paper, we review the extension of SPM imaging techniques to graphene. We image the cyclotron orbits passing between two narrow contacts in a single-atomic-layer graphene device in a perpendicular magnetic field. Magnetic focusing produces a peak in transmission between the contacts when the cyclotron diameter is equal to the contact spacing. The charged SPM tip deflects electrons passing from one contact to the other, changing the transmission when it interrupts the flow. By displaying the change in transmission as the tip is raster scanned above the sample, an image of flow is obtained. In addition, we have developed a complementary technique to image electronic charge using a cooledmore » scanning capacitance microscope (SCM) that uses a sensitive charge preamplifier near the SPM tip to achieve a charge noise level 0.13 e Hz^-1/2 with high spatial resolution 100 nm. The cooled SPM and SCM can be used to probe the motion of electrons on the nanoscale in graphene devices.« less

Authors:

Bhandari, Sagar ^[1]; Westervelt, Robert M. ^[2]

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+ Show Author Affiliations

1. Harvard Univ., Cambridge, MA (United States). School of Engineering and Applied Sciences
2. Harvard Univ., Cambridge, MA (United States). School of Engineering and Applied Sciences. Dept. of Physics

Publication Date:

Thu Jan 05 00:00:00 EST 2017

Research Org.:

Harvard Univ., Cambridge, MA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)

OSTI Identifier:

1423805

Grant/Contract Number:  

FG02-07ER46422; 1541959

Resource Type:

Accepted Manuscript

Journal Name:

Semiconductor Science and Technology

Additional Journal Information:

Journal Volume: 32; Journal Issue: 2; Journal ID: ISSN 0268-1242

Publisher:

IOP Publishing

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 47 OTHER INSTRUMENTATION; graphene; electron motion; scanning probe; magnetic focusing; scanning capacitance; imaging