Tunable Electronic Properties of Few-Layer Tellurene under In-Plane and Out-of-Plane Uniaxial Strain.

Genwang Wang,Ye Ding,Yanchao Guan,Lijun Yang,Yang Wang

doi:10.3390/nano12050875

Genwang Wang, Ye Ding + Show 3 more

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https://doi.org/10.3390/nano12050875

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Abstract

Strain engineering is a promising and fascinating approach to tailoring the electrical and optical properties of 2D materials, which is of great importance for fabricating excellent nano-devices. Although previous theoretical works have proved that the monolayer tellurene has desirable mechanical properties with the capability of withstanding large deformation and the tunable band gap and mobility conductance induced by in-plane strain, the effects of in-plane and out-of-plane strains on the properties of few-layer tellurene in different phases should be explored deeply. In this paper, calculations based on first-principles density functional theory were performed to predict the variation in crystal structures and electronic properties of few-layer tellurene, including the α and β phases. The analyses of mechanical properties show that few-layer α-Te can be more easily deformed in the armchair direction than β-Te owing to its lower Young’s modulus and Poisson’s ratio. The α-Te can be converted to β-Te by in-plane compressive strain. The variations in band structures indicate that the uniaxial strain can tune the band structures and even induce the semiconductor-to-metal transition in both few-layer α-Te and β-Te. Moreover, the compressive strain in the zigzag direction is the most feasible scheme due to the lower transition strain. In addition, few-layer β-Te is more easily converted to metal especially for the thicker flakes considering its smaller band gap. Hence, the strain-induced tunable electronic properties and semiconductor-to-metal transition of tellurene provide a theoretical foundation for fabricating metal–semiconductor junctions and corresponding nano-devices.

Highlights

Since a variety of two-dimensional (2D) materials have been synthesized by mechanical exfoliation, chemical vapor deposition (CVD), physical vapor deposition (PVD), molecular beam epitaxy (MBE), pulsed laser deposition (PLD), and so on [1,2], the mechanical, electrical, optical, and quantum properties make them attractive for applications in transistors, photodetectors, cells, sensors, and memristors [3–6]
The calculation results in this paper provide a foundation to design promising nano-devices based on tellurene
The mechanical and electronic properties of α and β tellurene under uniaxial strain were investigated by first-principles density functional theory calculations

Summary

Introduction

Since a variety of two-dimensional (2D) materials have been synthesized by mechanical exfoliation, chemical vapor deposition (CVD), physical vapor deposition (PVD), molecular beam epitaxy (MBE), pulsed laser deposition (PLD), and so on [1,2], the mechanical, electrical, optical, and quantum properties make them attractive for applications in transistors, photodetectors, cells, sensors, and memristors [3–6]. Despite the promising superiority of 2D materials, their intrinsic properties make them unsuitable for fabricating nano-devices with excellent properties and stability. Methods of tailoring intrinsic properties, such as doping [7,8], electric field tuning [9,10], surface modification [11], and building van der Waals heterostructure [12,13], have become critical ways to improve the performance further. Strain engineering emerges as a perfect candidate for controlling the performance of nano-devices, since the 2D materials are capable of withstanding large in-plane and out-of-plane strains before the rupture [14,15]. Strain can modulate the mechanical, electrical, and optical properties of 2D materials, like phase stability [16], band structure [17], mobility [18], Fermi level [19], and thermal conductivity [20], so that the strain-induced effects provide a fertile library for controlling the properties of advanced nano-devices.

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