Intervalley Scattering and the Role of Indirect Band Gap AlAs Barriers: Application to GaAs/AlGaAs Quantum Cascade Lasers

Abstract

We report on the results of our simulations of Γ −X scattering in GaAs/AlGaAs heterostructures, discussing the importance of the mole fraction, doping density, and lattice and electron temperature in determining the scattering rates. We consider three systems, a single quantum well (for the investigation of Γ −X scattering), a double quantum well (to compare the Γ −X−G and Γ −Γ scattering rates), and an example of a GaAs/AlGaAs mid-infrared quantum cascade laser. Our simulations suggest that Γ −X scattering can be significant at room temperature but falls off rapidly at lower temperatures. One important factor determining the scattering rate is found to be the energy difference between the Γ -and X-states.

Intervalley scattering of electrons by short-wave phonons in (GaAs)8(AlAs)8(001) superlattice

“…It is known that this scattering leads to a negative differential conductivity, leakage of currents in the cascade lasers, a reduction of electron mobility in the transistor channels, peculiarities in the photoluminescence spectra of hot electrons, the intersubband absorption in lasers at coupled quantum wells, etc [1,2]. Due to the effects of a size quantization the electronphonon interaction in (GaAs) m (AlAs) n (001) superlattices has a multi-channel character, so it is described by a great number of deformation potentials (DP) which makes it difficult to identify them from the analysis of experimental data and requires the use of theoretical methods.…”