Stress-strain in electron-beam activated polymeric micro-actuators

TL;DR

This paper investigates the stress-strain behavior of PMMA thin films under electron irradiation, providing insights into their mechanics for strain engineering in 2D material devices.

Contribution

It offers a detailed analysis of electron-induced stress in PMMA, including a universal shrinkage behavior and an estimated Young's modulus relevant for applications.

Findings

Stress values assessed via dielectric cantilevers.

Universal lateral shrinkage behavior of PMMA patterns.

Estimated Young's modulus for PMMA on graphene.

Abstract

Actuation of thin polymeric films via electron irradiation is a promising avenue to realize devices based on strain engineered two dimensional (2D) materials. Complex strain profiles demand a deep understanding of the mechanics of the polymeric layer under electron irradiation; in this article we report a detailed investigation on electron-induced stress on poly-methyl-methacrylate (PMMA) thin film material. After an assessment of stress values using a method based on dielectric cantilevers, we directly investigate the lateral shrinkage of PMMA patterns on epitaxial graphene, which reveals a universal behavior, independent of the electron acceleration energy. By knowing the stress-strain curve, we finally estimate an effective Young's modulus of PMMA on top of graphene which is a relevant parameter for PMMA based electron-beam lithography and strain engineering applications.