Screening-induced surface polar optical phonon scattering in dual-gated graphene field effect transistors

The effect of surface polar optical phonons (SOs) from the dielectric layers on electron mobility in dual-gated graphene field effect transistors (GFETs) is studied theoretically. By taking into account SO scattering of electron as a main scattering mechanism, the electron mobility is calculated by the iterative solution of Boltzmann transport equation. In treating scattering with the SO modes, the dynamic dielectric screening is included and compared to the static dielectric screening and the dielectric screening in the static limit. It is found that the dynamic dielectric screening effect plays an important role in the range of low net carrier density. More importantly, in-plane acoustic phonon scattering and charged impurity scattering are also included in the total mobility for SiO2-supported GFETs with various high-κ top-gate dielectric layers considered. The calculated total mobility results suggest both Al2O3 and AlN are the promising candidate dielectric layers for the enhancement in room temperature mobility of graphene in the future.