Electron transport in heavily doped bases of InP/GaInAs HBT´s probed by magneto transport experiments

Magneto transport experiments were carried out to study electron transport in the p-type base of InP/GaInAs heterojunction bipolar transistors (HBT´s). Electron minority carrier mobility was measured in the °K for two dopant concentrations in the base. The experimentally obtained mobility is compared to the theoretically predicted one. The scattering mechanisms considered in the calculations are screened ionized impurity scattering, alloy scattering, and coupled plasmon polar optical phonon scattering. The latter is calculated in the random phase approximation. The Boltzman transport equation (BTE) is solved to obtain the ratio between the measured mobility and the drift mobility. Good agreement was obtained between the measured results and the calculated ones for temperatures above 100 °K. At lower temperatures the calculated results differ from the experimental ones, probably due to hot electron effects