Piezoelectric field effects on electron density in a δ-doped AlGaAs/InyGa1-yAs/GaAs pseudomorphic HEMT

Abstract

We have calculated the low-temperature electron density in a δ-doped AlGaAs/InGaAs/GaAs heterostructure in the presence of a piezoelectric field. Growth of a strained InGaAs layer on (N11) GaAs substrates causes a piezoelectric field to be built into the quantum well of a pseudomorphic high electron mobility transistor (HEMT). The presence of this field modifies the electronic properties of strained-layer heterostructures. A self-consistent analysis is made of these δ-doping systems to solve simultaneously the Schrodinger and Poisson equations taking into account exchange-correlation and strain effects. Thus, we have found the confining potential, the electron density, the subband energies, the eigenenvelope wavefunctions, and the Fermi-energy level in the quantum well. We have studied the effects of the InGaAs channel width and the indium composition on the electron density. Our results show a larger increase of the electron density when the calculated value is for a (111) GaAs substrate rather than for equivalent (001) and (311) substrates. We have also investigated the effects of the environmental Al concentration seen by the Si δ-doped on the electron density.