Effect of half-space and interface phonons on the transport properties of ${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/GaAs single heterostructures

We present a detailed analysis of the influence of the various phonon modes characteristic of the single heterostructure ${\mathrm{Al}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/GaAs on its electronic transport by using a Monte Carlo simulation. The electronic states of the system are calculated by solving self-consistently the coupled Schrödinger-Poisson equations for the system. LO-phonon states are treated within the dielectric continuum model by using two different dielectric functions to describe the two semiconductors, the usual Lyddane-Sachs-Teller expression for GaAs and a generalized two poles expression for ${\mathrm{Al}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As. Two sets of optical modes characterize the system, the half-space LO modes and the interface modes. The scattering rates for the interaction of these modes with the confined electrons are calculated from the Fermi golden rule. A Monte Carlo simulation is then used to study the effect of the electron-phonon interaction on the transport properties of a single ${\mathrm{Al}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/GaAs heterostructure in the presence of an electric field applied along the heterointerface. The results of simulations performed at 300 and 77 K compare favorably with available experimental data. Drag and heating effects related to nonequilibrium phonon effects are found and discussed.