Numerical simulation of GaAs-based mid-infrared one-phonon resonance quantum cascade laser

Abstract

Non-equilibrium Green's function method is used to analyze electronic transport in a mid-infrared quantum cascade laser on microscopic level. Basing on the excellent agreement found between calculated and experimental data, the conclusions are derived that the carrier distribution in the lower laser subband is non-thermal, and the carriers are extracted from active region both in cold and hot state. An estimate s 3 ¼ 0:66 ps for upper lifetime at 77 K was found which considerably differs from the value 1.4 ps evaluated from the form factors.

Implementation of light–matter interaction in NEGF simulations of QCL

“…3 and compared to the experimental data of Page et al (2001). The agreement for current densities lower than ∼ 15 kA cm −2 is not bad if we take into account that the only adjustable parameter of the model is the roughness of the interfaces which was assumed as 1 3 of the monolayer spacing (Hałdaś et al 2017). The discrepancies observed for higher current densities can arise from several reasons.…”

“…2 was tested on GaAs/AlGaAs QCL, emitting at mid-IR wavelength ≅ 9.5 μm , described by Page et al (2001). The NEGF-based analysis of the electronic transport in this device, however without the light-matter interaction, has already been presented (Hałdaś et al 2017). The results that include this interaction are presented below.…”

“…The formulations for LO-phonon, interface roughness, ionized impurity, and alloy disorder selfenergies were taken from Lake et al's (1997) paper, whereas, for the acoustic phonons, the energy-averaged approximation of Kubis et al (2009) was used. The full set of model parameters used in the simulations can be found elsewhere (Hałdaś et al 2017). The calculations were made in the position basis: the base vectors were defined by the points discretizing the Hamiltonian of Eq.…”

Monte Carlo modeling applied to studies of quantum cascade lasers

“…The NEGF method (Wacker 2002;Lee and Wacker 2002;Lee et al 2006;Banit et al 2005; Schmielau and Pereira 2009;Hałdaś et al 2011Hałdaś et al , 2017Wacker et al 2013) can provide a fully quantum mechanical treatment of electron transport, where quantum mechanical effects such as coherent tunneling and incoherent scattering effects play an important role. An advantage unique to NEGF method is the ability to capture effects such as dispersive gain and gain linewidth reductions due to correlations.…”

Tuning quantum cascade laser wavelength by the injector doping

“…Out of all self-energies included into NEGF formalism, only those for IR scattering contain some arbitrary parameters, related to islands rms height h and average diameter Λ . These are hardly measurable quantities and usually are evaluated by adjusting experimental and calculated characteristics [24]. Such a procedure applied to our devices gives h = 0.19 nm and Λ = 9 nm.…”