We report a first-principles study on the elastic, vibrational, and electronic properties of the recently synthesized phosphorene. By calculating the Grüneisen parameters, we evaluate the frequency shift of the Raman and infrared active modes via symmetric biaxial strain. We also study a strain-induced semiconductor-metal transition, the gap size, and the effective mass of carriers in various strain configurations. Furthermore, we unfold the emergence of a peculiar Dirac-shaped dispersion for specific strain conditions including the zigzag-oriented tensile strain. The observed linear energy spectrum has distinct velocities corresponding to each of its linear branches and is limited to the -X direction in the first Brillouin zone.

In this paper the effect of biaxial and uniaxial strain on the mobility of single-layer MoS 2 for temperatures T > 100 K is investigated. Scattering from intrinsic phonon modes, remote phonon and charged impurities are considered along with static screening. Ab-initio simulations are utilized to investigate the strain induced effects on the electronic bandstructure and the linearized Boltzmann transport equation is used to evaluate the low-field mobility under various strain conditions. The results indicate that the mobility increases with tensile biaxial and tensile uniaxial strain along the armchair direction. Under compressive strain, however, the mobility exhibits a non-monotonic behavior when the strain magnitude is varied. In particular, with a relatively small compressive strain of 1% the mobility is reduced by about a factor of two compared to the unstrained condition, but with a larger compressive strain the mobility partly recovers such a degradation.

Propagation of acoustic waves in the one-dimensional ͑1D͒ random-dimer ͑RD͒ medium is studied by three distinct methods. First, using the transfer-matrix method, we calculate numerically the localization length of acoustic waves in a binary chain ͑one in which the elastic constants take on one of two values͒. We show that when there exists short-range correlation in the medium-which corresponds to the RD model-the localization-delocalization transition occurs at a resonance frequency c . The divergence of near c is studied, and the critical exponents that characterize the power-law behavior of near c are estimated for the regimes Ͼ c and Ͻ c . Second, an exact analytical analysis is carried out for the delocalization properties of the waves in the RD media. In particular, we predict the resonance frequency at which the waves can propagate in the entire chain. Finally, we develop a dynamical method, based on the direct numerical simulation of the governing equation for propagation of the waves, and study the nature of the waves that propagate in the chain. It is shown that only the resonance frequency can propagate through the 1D media. The results obtained with all the three methods are in agreement with each other.

In this paper, the effect of biaxial strain on the mobility of single-layer transition metal dichalcogenides (MoS2, MoSe2, WS2, WSe2) is investigated by accounting for the scattering from intrinsic phonon modes, remote phonons, and charged impurities.Ab-initio simulations are employed to study strain induced effect on the electronic bandstructure and the linearized Boltzmann transport equation is used to evaluate the low-field mobility. The results indicate that tensile strain increases the mobility. In particular, a significant increase in the mobility of single layer MoSe2 and WSe2 with a relatively small tensile strain is observed.Under compressive strain, however, the mobility exhibits a non-monotonic behavior. With a relatively small compressive strain the mobility decreases and then it partially recovers with further increase in compressive strain.

Here, we propose a strain gauge based on single-layer MoSe2 and WSe2 and show that, in these materials, the strain induced modulation of inter-valley phonon scattering leads to large mobility changes, which in turn result in highly sensitive strain gauges. By employing density-functional theory bandstructure calculations, comprehensive scattering models, and the linearized Boltzmann equation, we explain the physical mechanisms for the high sensitivity to strain of the resistivity in single-layer MoSe2 and WSe2, discuss the reduction of the gauge factor produced by extrinsic scattering sources (e.g., chemical impurities), and propose ways to mitigate such sensitivity degradation

The direct current electrical conductivity of ternary 40TeO 2 -(60 − x)V 2 O 5 -xMoO 3 glasses prepared by press-melt quenching technique was studied at temperatures between 90 and 403 K. From the conductivity-temperature relation, it was found that the small polaron hopping (SPH) model was applicable at the temperature above D /2 ( D : the Debye temperature), and the electrical conduction was due to the non-adiabatic SPH of electrons between vanadium ions for all glasses. The hopping carrier mobility and carrier density were determined at different temperatures. At temperatures lower than D /2, a T −1/4 dependence of the conductivity was found, which can be described by the variable-range hopping (VRH) conduction mechanism. The density of states at (or near) the Fermi level, N (E F ), was found from Mott parameters analysis,which was a function of V 2 O 5 content. All the semiconducting glass compositions exhibited a crossover from VRH to SPH conduction at a characteristic temperature T R D /2 .

The electronic transmission and conductance of a gapped graphene superlattice were calculated by means of the transfer-matrix method. The system that we study consists of a sequence of electron-doped graphene as wells and hole-doped graphene as barriers. We show that the transmission probability approaches unity at some critical value of the gap. We also find that there is a domain around the critical gap value for which the conductance of the system attains its maximum value.PACS numbers: 73.21. Cd, 72.10.Bg

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