Strain-tunable charge carrier mobility of atomically thin phosphorus allotropes

Abstract

We explore the impact of strain on charge carrier mobility of monolayer α, β, γ and δ-P, the four well known atomically thin allotropes of phosphorus, using density functional theory. Owing to the highly anisotropic band dispersion, the charge carrier mobility of the pristine allotropes is significantly higher (more than 5 times in some cases) in one of the principal directions (zigzag or armchair) as compared to the other. Uniaxial strain (upto 6% compressive/tensile) leads to bandgap alteration in each of the allotropes, especially a direct to indirect bandgap semiconductor transition in γ-P and a complete closure of the bandgap in γ and δ-P. We find that the charge carrier mobility is enhanced typically by a factor of ≈ 5 − 10 in all the allotropes due to uniaxial strain; notably among them a ≈ 250 (30) times increase of the hole (electron) mobility along the armchair (zigzag) direction is observed in β-P (γ-P) under a compressive strain, acting in the armchair direction. Interestingly, the preferred electronic conduction direction can also be changed in case of α and γ-P, by applying strain. arXiv:1803.02010v1 [cond-mat.mtrl-sci]

Valley-Engineering Mobilities in Two-Dimensional Materials

“…We stress that what is suggested here is at variance with recent theoretical studies that have proposed strain as a way to enhance mobility in various 2D materials [43][44][45][46][47][48][49][50][51] . These studies neglect intervalley scattering and consider the effect of strain on effective masses and, partially, on the intravalley scattering.…”

Interlayer decoupling in twisted bilayers of β-phosphorus and arsenic: A computational study

“…This will lead to highly anisotropic charge carrier effective mass, as reported in case of monolayer allotropes. 34,38 The indirect bandgap values are reported in Table I, and they are in good agreement with the values reported in the literature. 27,47 However, the bandgap in GGA based calculations are known to be underestimated, and nearly two fold increase is reported with use of more accurate hybrid functionals.…”

“…In terms of electronic transport properties, both the allotropes are found to be comparable. 38 Interestingly, a hole doping induced ferromagnetic ground state has been reported in case of β-P. 39,40 Our study reveals that the p z orbitals contribute significantly to the valance as well as conduction band edge of the bilayers of AA-stacked β-P and β-As. Thus, the interactions among the p z orbitals on different layers are impacted significantly by the relative rotation of the layers relative to each other.…”

Structural, Electronic, and Optical Properties of Hexagonal XC6 (X=N, P, As, and Sb) Monolayers

“…The carrier mobility of XC 6 (X=N, P, As and Sb) and many other previously reported 2D materials are listed in Table S2 in the Supporting Information. Noticeably, the estimated values of electron mobility in the range of 1200–1900 cm 2 V −1 s −1 are higher than those of many known 2D semiconductors, such as MoS 2 (200–270 cm 2 V −1 s −1 ), [10,39] blue phosphorus (426‐522 cm 2 V −1 s −1 ), [40] GeP 3 monolayer (190‐360 cm 2 V −1 s −1 ), [17c] Sn x P y monolayers (∼800 cm 2 V −1 s −1 ), [41] twin T‐graphene (379 cm 2 V −1 s −1 ), [7e] and InX (X=S, Se and Te) monolayers (257‐728 cm 2 V −1 s −1 ) [14b] …”