First-principles calculations reveal controlling principles for carrier mobilities in semiconductors...

It has long been believed that carrier mobilities in semiconductors can be calculated by Fermi’s golden rule (Born approximation). Phenomenological models for scattering amplitudes are typically used for engineering- level device modeling. Here we introduce a parameter-free, first-principles approach based on complex- wavevector energy bands that does not invoke the Born approximation. We show that phonon-limited mobility is controlled by low-resistivity percolation paths and that in ionized-impurity scattering one must account for the effect of the screening charge, which cancels most of the Coulomb tail. Calculated electron mobilities in silicon are in agreement with experimental data.