Charge Scattering and Mobility in Atomically Thin Semiconductors

The electron transport properties in atomically thin semiconductors have attracted intense interest. In this work, we study the scattering mechanisms that limiting the mobility of such semiconductors. The effects of the dielectric environments are also evaluated. We find that high-K dielectrics increase the charged-impurity-limited mobility, but weaken the free-carrier screening. The strong remote optical phonon scattering from high-K dielectrics severely decrease the high-temperature mobility. From a comparative study of different scattering mechanisms, we find that all current reported measured mobilities (around 100 cm$^{\mathrm{2}}$/Vs) are dominated by charged impurity scattering. When the impurity densities are reduced, remote phonon scattering determines the room-temperature mobility upper-limits. The mobilities achieved till date are far below the intrinsic potential in these materials. The truly intrinsic mobility over 10,000 cm$^{\mathrm{2}}$/Vs at room temperature can only be achieved in ultraclean suspended samples. Among the commonly used dielectrics, AlN and BN offer the best compromise if a high mobility over 1000 cm$^{\mathrm{2}}$/Vs and a high gate capacitance are simultaneously desired, as is the case in field effect transistors.