Strain-driven superplasticity and modulation of electronic properties of ultrathin tin (II) oxide: A first-principles study

TL;DR

This study reveals that ultrathin tin (II) oxide exhibits superplasticity under uniaxial strain, with significant implications for strain-engineered nanoelectronic devices, supported by first-principles calculations of its mechanical and electronic properties.

Contribution

It provides the first detailed first-principles analysis of the mechanical and electronic behavior of ultrathin SnO under tensile strain, highlighting superplasticity and phase transformations.

Findings

Monolayer SnO has a critical failure strain of up to 74%.

Superplasticity is linked to formation of a tri-coordinated intermediate phase.

Strain significantly modulates SnO's electronic properties, including work function and band gap.

Abstract

2D-layered tin (II) oxide (SnO) has recently emerged as a promising bipolar channel material for thin-film transistors and complementary metal-oxide-semiconductor devices. In this work, we present a first-principles investigation of the mechanical properties of ultrathin SnO, as well as the electronic implications of tensile strain ($\epsilon$) under both uniaxial and biaxial conditions. Bulk-to-monolayer transition is found to significantly lower the Young's and shear moduli of SnO, highlighting the importance of interlayer Sn-Sn bonds in preserving structural integrity. Unprecedentedly, few-layer SnO exhibits superplasticity under uniaxial deformation conditions, with a critical strain to failure of up to 74% in the monolayer. Such superplastic behavior is ascribed to the formation of a tri-coordinated intermediate (referred to here as h-SnO) beyond $\epsilon$ = 14%, which resembles a partially-recovered orthorhombic phase with relatively large work function and wide indirect band gap. The broad structural range of tin (II) oxide under strongly anisotropic mechanical loading suggests intriguing possibilities for realizing novel hybrid nanostructures of SnO through strain engineering. The findings reported in this study reveal fundamental insights into the mechanical behavior and strain-driven electronic properties of tin (II) oxide, opening up exciting avenues for the development of SnO-based nanoelectronic devices with new, non-conventional functionalities.