Self-consistent k⋅p band structure calculation for AlGaAs/InGaAs pseudomorphic high electron mobility transistors

Abstract

A self-consistent four-band k⋅p calculation for the band structure of AlGaAs/InGaAs pseudomorphic high electron mobility transistors (p-HEMTs) is presented. The eigenstates are described in a basis consisting of electron, heavy-hole, light-hole, and split-off bulk states. The k⋅p Hamiltonian derived in this basis includes strain-induced mixing between the conduction and light-hole and the conduction and split-off bands. It also includes additional splitting between the heavy- and light-hole bands, apart from that induced by the shear deformation potential, caused by strain-induced changes in the spin-orbit interaction. The Hartree potential is calculated from the Poisson equation and the exchange-correlation potential from density-functional theory within the local-density approximation. The model calculation accounts for deep level surface acceptor and donor states, both of which contribute to Fermi level pinning at the surface. Also included are acceptor interface states at the inverted GaAs/AlGaAs interface. The present calculation can be used as a characterization tool to analyze optical and Hall data from preprocessed p-HEMT material, since conduction-valence subband separations and mobile sheet charge densities are results of the calculation.