Importance of electron-impurity scattering for electron transport in terahertz quantum-cascade lasers
نویسندگان
چکیده
Using an ensemble Monte Carlo simulation, including both electron–electron and electron–phonon scattering as well as electron-impurity scattering, the current density, population inversion, electron temperature, and gain in two THz quantum-cascade structures are investigated and compared to measurements. We find that the inclusion of electron-impurity scattering in the calculations is crucial when modeling the intersubband transport dynamics in these devices. However, the calculated gain is higher than inferred from experiments. This can be attributed to wavefunction localization caused by dephasing scattering, which is unaccounted for in the present model. © 2004 American Institute of Physics. @DOI: 10.1063/1.1644337#
منابع مشابه
Importance of coherence for electron transport in terahertz quantum cascade lasers
A density matrix approach is used in combination with a tight-binding model to describe electron transport in terahertz quantum cascade lasers and is incorporated into a Monte Carlo simulation. Scattering events, including LO-phonon, electron-electron, and ionized impurity scattering, are treated semiclassically but contribute to dephasing scattering. In addition, a phenomenological “pure depha...
متن کاملTheory of nonequilibrium quantum transport and energy dissipation in terahertz quantum cascade lasers
We analyze theoretically several crucial performance aspects of terahertz quantum cascade lasers, such as the impact of doping on the threshold current, the relative importance of the various scattering mechanisms, and the balance of coherent transport and realistic energy dissipation. We have developed a fully self-consistent model for stationary charge transport based on nonequilibrium Green’...
متن کاملThe relative importance of electron-electron and electron-phonon scattering in terahertz quantum cascade lasers
This theoretical work explores the carrier dynamical issues that must be confronted if the recent successes of the mid-infrared quantum cascade laserss1] are to be translated into longer wavelength devices. Whilst the small subband separations lead to a partial suppression of longitudinal optic (LO) phonon emission, which is the dominant non-radiative loss mechanism in quantum cascade lasers, i...
متن کاملIndirectly Pumped 3.7 THz InGaAs/InAlAs Quantum-Cascade Lasers Grown by Metal-Organic Vapor-Phase Epitaxy
Device-performances of 3.7 THz indirect-pumping quantumcascade lasers are demonstrated in an InGaAs/InAlAs material system grown by metal-organic vapor-phase epitaxy. The lasers show a low threshold-current-density of ~420 A/cm and a peak output power of ~8 mW at 7 K, no sign of parasitic currents with recourse to well-designed coupled-well injectors in the indirect pump scheme, and a maximum o...
متن کاملNonequilibrium phonon effects on electron transport in GaAs-based mid-infrared quantum cascade lasers
The dominant energy relaxation mechanism of electrons in quantum cascade lasers (QCLs) is the non-radiative scattering with optical phonons [1]. Through optical phonon emissions, the injected electrons in the upper lasing level are rapidly transferred to the lower lasing level, and the carrier life time in the upper lasing subband is significantly reduced. Consequently, a large current must be ...
متن کامل