Recently, a novel two-dimensional (2D) semiconductor, InSe, has attracted great attention due to its potential applications in optoelectronic devices and field effect transistors. In this study, phonon-limited mobility is investigated by the first-principles calculation. At 300 K, the intrinsic electron mobilities calculated from the electron-phonon coupling (EPC) matrix element are as high as µ x = 9.85 × 10 2 (zigzag direction) and µ y = 1.06 × 10 3 cm 2 V −1 s −1 (Armchair direction), respectively. The deformation potential theory (DPT) based on longitudinal acoustic and optical phonon scattering is also employed to investigate electron mobility. The mobility from optical phonon scattering is much higher than that from longitudinal acoustic phonon scattering. If the polarization characteristics of InSe are not considered, the electron mobility calculated from EPC matrix element is closed to that from the longitudinal acoustic phonon DPT. In this study, we have also investigated the effect of polarization properties in 2D InSe on electron mobility. At 300 K, the electron mobility for including Fröhlich interaction is reduced to µ x = 2.96 × 10 2 and µ y = 3.34 × 10 2 cm 2 V −1 s −1 . Therefore, the electron mobility for InSe is controlled by the scattering from polar phonons. The mobility can be increased to µ x = 3.46 × 10 2 and µ y = 3.78 × 10 2 cm 2 V −1 s −1 under 4% biaxial strain. This result is compared with the experiment, and some disagreements are explained.

ABSTRACT:The multiphoton association reaction He þ H þ ! HeH þ in the electronic ground state is investigated using the time-dependent quantum wave packet method. It is shown that the collision pairs He þ H þ in continuum state transfer into m ¼ 0 state and then produce stable molecules HeH þ through emission of two or three photons. The multiphoton transition takes place via intermediate states, and the transfer probability is determined by the collision energy and the intermediate states. The populations of the intermediate states and m ¼ 0 state can be controlled by the laser duration. The three-photon transition is more efficient than the two-photon transition for producing the molecule HeH þ in m ¼ 0 state.

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