Contrasting influence of charged impurities on transport and gain in terahertz quantum cascade lasers

Abstract

Transport and gain properties of a resonant-phonon terahertz quantum cascade laser are calculated using nonequilibrium Green's functions. Impurity scattering is shown to be responsible for contrasting nonlinear effects in the transport and the gain properties. For typical doping concentrations, the current density is found to be weakly sensitive to the impurity scattering strength. In contrast, the calculated gain is found to be very sensitive to the impurity scattering strength. This difference is attributed to the strong momentum dependence of the long-range coupling to charged impurities. Small-momentum impurity scattering is shown to be responsible for an incoherent regime of resonant tunneling processes. These new insights into the crucial role of impurity scattering open a new route of improvement of terahertz quantum cascade lasers by engineering of the doping profile.

4 pages, 4 figures

References in corpus (7)

• Modeling techniques for quantum cascade lasers
• Quantum-mechanical wavepacket transport in quantum cascade laser structures
• Self-Consistent Theory of the Gain Linewidth for Quantum Cascade Lasers
• Temperature dependence of the gain profile for THz quantum cascade lasers
• Monte-Carlo-based spectral gain analysis for THz quantum cascade lasers
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Cited by in corpus (6)

• Room temperature operation of n-type Ge/SiGe terahertz quantum cascade lasers predicted by non-equilibrium Green's functions
• Atomic-scale insights into semiconductor heterostructures: from experimental three-dimensional analysis of the interface to a generalized theory of interface roughness scattering
• Density matrix Monte Carlo modeling of quantum cascade lasers
• THz intersubband electroluminescence from n-type Ge/SiGe quantum cascade structures
• Simulating terahertz quantum cascade lasers: Trends from samples from different labs
• Superlattice gain in positive differential conductivity region