Monte Carlo Study of Electronic Transport in Monolayer InSe.

Sanjay Gopalan,Maarten L Van De Put,Gautam Gaddemane,And Massimo V Fischetti

doi:10.3390/ma12244210

Sanjay Gopalan, Maarten L Van De Put + Show 2 more

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https://doi.org/10.3390/ma12244210

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Journal: Materials	Publication Date: Dec 14, 2019
Citations: 16	License type: CC BY 4.0

Affiliation: The University of Texas at Dallas

Abstract

The absence of a band gap in graphene makes it of minor interest for field-effect transistors. Layered metal chalcogenides have shown great potential in device applications thanks to their wide bandgap and high carrier mobility. Interestingly, in the ever-growing library of two-dimensional (2D) materials, monolayer InSe appears as one of the new promising candidates, although still in the initial stage of theoretical studies. Here, we present a theoretical study of this material using density functional theory (DFT) to determine the electronic band structure as well as the phonon spectrum and electron-phonon matrix elements. The electron-phonon scattering rates are obtained using Fermi’s Golden Rule and are used in a full-band Monte Carlo computer program to solve the Boltzmann transport equation (BTE) to evaluate the intrinsic low-field mobility and velocity-field characteristic. The electron-phonon matrix elements, accounting for both long- and short-range interactions, are considered to study the contributions of different scattering mechanisms. Since monolayer InSe is a polar piezoelectric material, scattering with optical phonons is dominated by the long-range interaction with longitudinal optical (LO) phonons while scattering with acoustic phonons is dominated by piezoelectric scattering with the longitudinal (LA) branch at room temperature (T = 300 K) due to a lack of a center of inversion symmetry in monolayer InSe. The low-field electron mobility, calculated considering all electron-phonon interactions, is found to be 110 cm2V−1s−1, whereas values of 188 cm2V−1s−1 and 365 cm2V−1s−1 are obtained considering the long-range and short-range interactions separately. Therefore, the calculated electron mobility of monolayer InSe seems to be competitive with other previously studied 2D materials and the piezoelectric properties of monolayer InSe make it a suitable material for a wide range of applications in next generation nanoelectronics.

Highlights

The great success of graphene [1,2] has been followed by an impressive surge of the study of other two-dimensional (2D) materials
In 2D materials like silicene and germanene, that lack horizontal mirror symmetry, Fischetti et al [24] and Gaddemanne et al [8] have shown that the coupling of electrons to the ZA phonons is extremely strong, an effect that results in extremely low mobilities [24]
We have found that the effect of the spin-orbit coupling (SOC) on the band structure is negligible and it does not change the electron effective mass of the material

Summary

Introduction

The great success of graphene [1,2] has been followed by an impressive surge of the study of other two-dimensional (2D) materials. 2D materials, including graphene [1,2], phosphorene [3,4,5,6,7], silicene [8,9,10], silicane [9,11,12,13], germanene [8,9,10,14], and transition metal dichalcogenides [15,16,17,18,19,20], have been widely studied for their unique electrical and optical properties. The intrinsic thermodynamic instability of 2D materials, which originates from Mermin–Wagner theorem [22,23], has been challenged on theoretical grounds. This instability stems from the parabolic dispersion of the acoustic flexural (“out-of-plane” or ZA) modes which causes their thermal population. The electron-phonon matrix element vanishes and intraband electronic transitions assisted by these flexural modes are forbidden to first order [24]

Results

Discussion

Conclusion