Ripple Texturing of Suspended Graphene Atomic Membranes

TL;DR

This paper demonstrates the creation and control of ripples in suspended graphene membranes, measures its unusual negative thermal expansion, and discusses implications for strain engineering of graphene-based devices.

Contribution

It reports the first direct observation of 1D and 2D ripples in suspended graphene and measures its anomalously large negative thermal expansion coefficient.

Findings

Controlled ripple formation in graphene sheets

Measurement of negative thermal expansion coefficient

Potential for strain-engineered graphene devices

Abstract

Graphene is the nature's thinnest elastic membrane, with exceptional mechanical and electrical properties. We report the direct observation and creation of one-dimensional (1D) and 2D periodic ripples in suspended graphene sheets, using spontaneously and thermally induced longitudinal strains on patterned substrates, with control over their orientations and wavelengths. We also provide the first measurement of graphene's thermal expansion coefficient, which is anomalously large and negative, ~ -7x10^-6 K^-1 at 300K. Our work enables novel strain-based engineering of graphene devices.