Majority and minority mobilities in heavily doped gallium aluminum arsenide for device simulations

Abstract

Summary form only given. Simulators for heterojunction bipolar transistors (HBTs) require physical models and associated input parameters that describe how carrier transport varies with carrier concentrations, ionized dopant densities, alloy mole fractions, and temperature. In order to increase the probability that simulations of HBTs are predictive and useful for the future development of HBTs, accurate and independent values for the majority and minority mobilities of electrons and holes in Ga/sub 1-y/Al/sub y/As are essential for reducing the number of unknown or fitting parameters. The majority electron and minority hole mobilities in Ga/sub 1-y/Al/sub y/As for donor densities, N/sub d/, between 10/sup 16/ cm/sup -3/ and 10/sup 19/ cm/sup -3/ are calculated by first-principles methods based on quantum mechanics. Similarly, the majority hole and minority electron mobilities for acceptor densities, N/sub d/, between 10/sup 16/ cm/sup -3/ and 10/sup 20/ cm/sup -3/ are calculated. The mole fraction of AlAs, y, varies between 0.0 and 0.3 in these calculations. All the important scattering mechanisms for low-field mobilities are included; namely, alloy scattering, acoustic phonon, polar optic phonon, nonpolar optic phonon (holes only), piezoelectric, ionized impurity, carrier-carrier, and plasmon scattering. The ionized impurity and carrier-carrier scattering processes are treated with a quantum-mechanical, phase-shift analysis. These calculations are the first to use a phase-shift analysis for minority carriers scattering from majority carriers in ternary compounds such as Ga/sub 1-y/Al/sub y/As.