A first principles method to simulate electron mobilities in 2D materials

Restrepo, Oscar D.; Krymowski, Kevin; Goldberger, Joshua E.; Windl, Wolfgang

doi:10.1088/1367-2630/16/10/105009

Cited by 66 publications

(63 citation statements)

References 40 publications

(52 reference statements)

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“…Moreover, our results agree well with Ref. [53], which reports an effective mass of 1 for the conduction band of graphane using first-principles calculations. However, the comparison is more complex in the case of the valence bands.…”

Section: Graphanesupporting

confidence: 92%

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Precise effective masses from density functional perturbation theory

et al. 2016

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The knowledge of effective masses is a key ingredient to analyze numerous properties of semiconductors, like carrier mobilities, (magneto)transport properties, or band extrema characteristics yielding carrier densities and density of states. Currently, these masses are usually calculated using finite-difference estimation of density functional theory (DFT) electronic band curvatures. However, finite differences require an additional convergence study and are prone to numerical noise. Moreover, the concept of effective mass breaks down at degenerate band extrema. We assess the former limitation by developing a method that allows to obtain the Hessian of DFT bands directly, using density functional perturbation theory. Then, we solve the latter issue by adapting the concept of "transport equivalent effective mass" to the k·p framework. The numerical noise inherent to finite-difference methods is thus eliminated, along with the associated convergence study. The resulting method is ther... The knowledge of effective masses is a key ingredient to analyze numerous properties of semiconductors, like carrier mobilities, (magneto)transport properties, or band extrema characteristics yielding carrier densities and density of states. Currently, these masses are usually calculated using finite-difference estimation of density functional theory (DFT) electronic band curvatures. However, finite differences require an additional convergence study and are prone to numerical noise. Moreover, the concept of effective mass breaks down at degenerate band extrema. We assess the former limitation by developing a method that allows to obtain the Hessian of DFT bands directly, using density functional perturbation theory. Then, we solve the latter issue by adapting the concept of "transport equivalent effective mass" to the k ·p framework. The numerical noise inherent to finite-difference methods is thus eliminated, along with the associated convergence study. The resulting method is therefore more general, more robust, and simpler to use, which makes it especially appropriate for high-throughput computing. After validating the developed techniques, we apply them to the study of silicon, graphane, and arsenic. The formalism is implemented into the ABINIT software and supports the norm-conserving pseudopotential approach, the projector augmented-wave method, and the inclusion of spin-orbit coupling. The derived expressions also apply to the ultrasoft pseudopotential method.

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Section: Graphanesupporting

confidence: 92%

“…However, the effective masses in this material have received little attention. Indeed, to the author's knowledge, only the effective mass of the conduction band has been roughly assessed [53]. We thus decided to investigate this topic from our first-principles framework.…”

Section: Graphanementioning

confidence: 99%

Precise effective masses from density functional perturbation theory

et al. 2016

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“…Recently, several groups have combined DFT with density functional perturbation theory [43,44,[50][51][52] to evaluate the mobility from first principles. Parameter-free methods can be used to address how close experiments are to ideal conductivities and if further optimization of fabrication techniques and device designs for novel 2D materials could improve device performance.…”

Section: Introductionmentioning

confidence: 99%

First-principles method for electron-phonon coupling and electron mobility: Applications to two-dimensional materials

et al. 2016

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We present density functional theory calculations of the phonon-limited mobility in n-type monolayer graphene, silicene and MoS2. The material properties, including the electron-phonon interaction, are calculated from first-principles. We provide a detailed description of the normalized full-band relaxation time approximation for the linearized Boltzmann transport equation (BTE) that includes inelastic scattering processes. The bulk electron-phonon coupling is evaluated by a supercell method. The method employed is fully numerical and does therefore not require a semianalytic treatment of part of the problem and, importantly, it keeps the anisotropy information stored in the coupling as well as the band structure. In addition, we perform calculations of the low-field mobility and its dependence on carrier density and temperature to obtain a better understanding of transport in graphene, silicene and monolayer MoS2. Unlike graphene, the carriers in silicene show strong interaction with the out-of-plane modes. We find that graphene has more than an order of magnitude higher mobility compared to silicene. For MoS2, we obtain several orders of magnitude lower mobilities in agreement with other recent theoretical results. The simulations illustrate the predictive capabilities of the newly implemented BTE solver applied in simulation tools based on first-principles and localized basis sets.

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“…These techniques have since then been widely used to investigate EPI and to compute thermoelectric properties [37][38][39] and electron mean free path (MFP) spectra [39] in silicon as well as the electrical resistivity in graphene [40][41][42] under RTA. Such density-functional-theory-based (DFT-based) treatment can also be employed to compute electron mobility in weakly polar materials such as transition metal dichalcogenides [43][44][45][46] and perovskites [47,48], in which RTA still works due to the suppression of LO-phonon scatterings by strong dielectric screening. For strongly polar materials, like GaAs, the long-range information originating from polar-optical-phonon and piezoelectric interactions in e-ph coupling matrices are lost during the Wannier interpolation [35].…”

Section: Introductionmentioning

confidence: 99%

First-principles mode-by-mode analysis for electron-phonon scattering channels and mean free path spectra in GaAs

et al. 2017

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We present a first-principles framework to investigate the electron scattering channels and transport properties for polar materials by combining the exact solution of linearized electronphonon (e-ph) Boltzmann transport equation in its integral-differential form associated with the e-ph coupling matrices obtained from polar Wannier interpolation scheme. No ad hoc parameter is required throughout this calculation, and GaAs, a well-studied polar material, is used as an example to demonstrate this method. In this work, the long-range and short-range contributions as well as the intravalley and intervalley transitions in the e-ph interactions (EPIs) have been quantitatively addressed. Promoted by such mode-by-mode analysis, we find that in GaAs, the piezoelectric scattering is comparable to deformation-potential scattering for electron scatterings by acoustic phonons in EPI even at room temperature and makes a significant contribution to mobility. Furthermore, we achieved good agreement with experimental data for the mobility, and identified that electrons with mean free paths between 130 and 210 nm provide the dominant contribution to the electron transport at 300 K. Such information provides a deeper understanding on the electron transport in GaAs, and the presented framework can be readily applied to other polar materials.

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A first principles method to simulate electron mobilities in 2D materials

Cited by 66 publications

References 40 publications

Precise effective masses from density functional perturbation theory

Precise effective masses from density functional perturbation theory

First-principles method for electron-phonon coupling and electron mobility: Applications to two-dimensional materials

First-principles mode-by-mode analysis for electron-phonon scattering channels and mean free path spectra in GaAs

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