Strain-engineered diffusive atomic switching in two-dimensional crystals

Janne Kalikka,Eric Dilcher,Simon Wall,Ju Li,Robert E Simpson,Xilin Zhou

doi:10.1038/ncomms11983

Abstract

Strain engineering is an emerging route for tuning the bandgap, carrier mobility, chemical reactivity and diffusivity of materials. Here we show how strain can be used to control atomic diffusion in van der Waals heterostructures of two-dimensional (2D) crystals. We use strain to increase the diffusivity of Ge and Te atoms that are confined to 5 Å thick 2D planes within an Sb2Te3–GeTe van der Waals superlattice. The number of quintuple Sb2Te3 2D crystal layers dictates the strain in the GeTe layers and consequently its diffusive atomic disordering. By identifying four critical rules for the superlattice configuration we lay the foundation for a generalizable approach to the design of switchable van der Waals heterostructures. As Sb2Te3–GeTe is a topological insulator, we envision these rules enabling methods to control spin and topological properties of materials in reversible and energy efficient ways.

Highlights

Strain engineering is an emerging route for tuning the bandgap, carrier mobility, chemical reactivity and diffusivity of materials
In this work we show that biaxial strain selectively destabilizes GeTe layers within the Sb2Te3–GeTe heterostructure and allows diffusive atomic disordering within the GeTe layers
The most familiar example is in metal oxide semiconductor fieldeffect transistors (MOSFETs)[6] where the Si channel is strained by a lattice mismatch between it and the surrounding material[7]

Summary

Introduction

Strain engineering is an emerging route for tuning the bandgap, carrier mobility, chemical reactivity and diffusivity of materials. We show how strain can be used to control atomic diffusion in van der Waals heterostructures of two-dimensional (2D) crystals. We use strain to increase the diffusivity of Ge and Te atoms that are confined to 5 Å thick 2D planes within an Sb2Te3–GeTe van der Waals superlattice. Van der Waals (vdW) heterostructures composed from layers of two-dimensional (2D) atomic crystals[1] provide unprecedented freedom to systematically design the properties of materials. Their properties are dependent on the sequence of the layers[2], interlayer separation[3] and the stress in the layers[4]. The SLL’s switching energy reduction stems from its low thermal conductivity[15] and associated heating efficiency, not from controlled interfacial atomic diffusion

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Methods

Conclusion