Phonon Limited Mobility Of BC₂N,BC₆N And InSe

Phonon limited mobility is one of the important reference factors for designing FET devices.Therefore,accurate and reasonable prediction of mobility is very important for the application of materials.Based on the first principles,we studied the phonon limited mobility of BC₂N,BC₆N and In Se,and explore the main scattering mechanism.In the study of monolayer BC₂N,based on first principles,we have systematically studied the carrier mobility.First,we calculate the carrier mobility using longitudinal acoustic and optical phonon DPT.The mobility shows obvious anisotropic behavior.The values from longitudinal acoustic phonon scattering are higher than those from optical phonon scattering.Therefore,the mobility is mainly controlled the optical phonon scattering.At 300 K,electron mobility is 3.82×10²cm²V^-1s^-1along x direction,and3.41×10¹cm²V^-1s^-1along y direction,while hole mobility is 3.48×10²cm²V^-1s^-1along x direction,and 2.63×10¹cm²V^-1s^-1along y direction.Then the intrinsic mobility is investigated by EPC matrix elements.If the polarization characteristic is considered in the calculation,the mobility along x direction is reduced to be 58?110 cm²V^-1s^-1for electron,and 41?70 cm²V^-1s^-1for hole.Because some empirical models do not consider Fr(?)hlich interaction,the mobility is greatly over estimated.In the study of monolayer BC₆N,the carrier mobility is studied by first principles.First,the electron-phonon interaction matrix element(EPIME)from standard Wannier and polar Wannier interpolation schemes is employed to investigate mobility.After considering the polarization,carrier mobility is greatly reduced,so polar optical phonon(POP)scattering plays an important role.At 300 K,the electron mobility for the most stable BC₆N-B is predicted to?_x=4.51×10²?8.37×10²cm²V^-1s^-1and?_y=8.35×10²?1.22×10³cm²V^-1s^-1,while the hole mobility is estimated to?_x=4.79×10²?8.65×10²cm²V^-1s^-1??_y=9.19×10²?1.28×10³cm²V^-1s^-1.Then,longitudinal acoustic phonon deformation potential theory(LAP-DPT)is adopted to calculate the mobility,which leads to an overestimation for carrier mobility in polar semiconductor.Furthermore,the semiempirical model based on the POP scattering is also used to investigate the mobility.It is confirmed that the intrinsic mobility for BC₆N is mainly determined by the Fr(?)hlich interaction.The investigation provides a deep understanding of carrier transport properties.It is revealed that B and N co-doped graphene may become a promising material for applications in nanoelectronic devices due to the excellent mechanical behavior,moderate direct band gap and high carrier mobility.In the study of monolayer of In Se,Based on the first principles,we calculated its intrinsic electron mobility and explored the effect of strain on mobility.At 300 K,the intrinsic electron mobility calculated from the electron-phonon coupling(EPC)matrix element is as high as?_x=9.85×10²cm²V^-1s^-1and?_y=1.06×10³cm²V^-1s^-1,respectively.The deformation potential theory(DPT)based on longitudinal acoustic phonon and optical phonon scattering is also employed to investigate electron mobility,and it is found that the intrinsic electron mobility of In Se is determined by the longitudinal acoustic phonon scattering..If the polarization characteristic of In Se is not considered,the electron mobility calculated from EPC matrix element is closed to that from the longitudinal acoustic phonon DPT.If polarization characteristic is considered,at 300 K,the electron mobility for including Fr(?)hlich interaction is reduced to?_x=2.96×10²cm²V^-1s^-1and?_y=3.34×10³cm²V^-1s^-1.Therefore,the electron mobility for In Se is controlled by the scattering from polar phonons.When exploring the effect of biaxial strain on mobility,the mobility can be increased to?_x=3.46×10²cm²V^-1s^-1and?_y=3.78×10³cm²V^-1s^-1at 4% biaxial strain.