An extended density matrix model applied to silicon-based terahertz quantum cascade lasers

Abstract

Silicon-based terahertz quantum cascade lasers (QCLs) offer potential advantages over existing III-V devices. Although coherent electron transport effects are known to be important in QCLs, they have never been considered in Si-based device designs. We describe a density matrix transport model that is designed to be more general than those in previous studies and to require less a priori knowlege of electronic bandstructure, allowing its use in semi-automated design procedures. The basis of the model includes all states involved in interperiod transport, and our steady-state solution extends beyond the rotating-wave approximation by including DC and counter-propagating terms. We simulate the potential performance of bound-to-continuum Ge/SiGe QCLs and find that devices with 4-5-nm-thick barriers give the highest simulated optical gain. We also examine the effects of interdiffusion between Ge and SiGe layers; we show that if it is taken into account in the design, interdiffusion lengths of up to 1.5 nm do not significantly affect the simulated device performance.

8 pages, 4 figures

References in corpus (8)

• Coherence of resonant-tunneling transport in terahertz quantum-cascade lasers
• Gain in quantum cascade lasers and superlattices: A quantum transport theory
• Density-matrix theory of the optical dynamics and transport in quantum cascade structures: The role of coherence
• Density matrix theory of transport and gain in quantum cascade lasers in a magnetic field
• Material configurations for n-type silicon-based terahertz quantum cascade lasers
• Intersubband carrier scattering in n- and p-Si/SiGe quantum wells with diffuse interfaces
• Theory and design of quantum cascade lasers in (111) n-type Si/SiGe
• Intervalley splitting and intersubband transitions in n-type Si/SiGe quantum wells: pseudopotential vs. effective mass calculation

Cited by in corpus (4)

• Room temperature operation of n-type Ge/SiGe terahertz quantum cascade lasers predicted by non-equilibrium Green's functions
• Optoelectronic device simulations based on macroscopic Maxwell-Bloch equations
• Density matrix Monte Carlo modeling of quantum cascade lasers
• Density Matrix Modeling of Quantum Cascade Lasers without an Artificially Localized Basis: A Generalized Scattering Approach