Scattering of carriers by coupled plasmon-phonon modes in bulk polar semiconductors and polar semiconductor heterostructures

摘要

We present a general treatment of carrier scattering by coupled phonon-plasmon collective modes inpolar semiconductors, taking anharmonic phonon decay into account and self-consistently calculating carriermomentum relaxation rates and carrier mobility in a parabolic band model. We iteratively solve the weak-fieldBoltzmann equations for carriers and collective modes and obtain their nonequilibrium distribution functions.Both the scattering rates and the anharmonic decay of the coupled modes are expressed through the total dielectricfunction of the semiconductor, consisting of a damped lattice dielectric function, and a temperature dependentrandom phase approximation dielectric function for the carrier plasma. We show that the decay of the coupledmodes has a significant effect on the contribution to the mobility limited by carrier-coupled mode scattering.We also propose a scalar quantity, the phonon dissipation weight factor, with which this effect can be estimatedfrom an analytic expression. We apply this treatment to dynamically screened electron-longitudinal opticalphonon scattering in bulk polar semiconductors, and to dynamically screened remote phonon scattering in polarheterostructures where monolayers of MoS_2 are sandwiched between various polar dielectrics. We find that adynamic treatment of the remote phonon scattering yields mobilities up to 75% higher than a static screeningapproximation does for structures which consist of a monolayer of MoS_2 between hafnia and silica. Moreover,we show that accounting for the nonzero thickness of the MoS_2 interface layer has an important effect on thecalculated mobility in the same structure.