Influence of doping density on electron dynamics in GaAs∕AlGaAs quantum cascade lasers

Jovanović, V. D.; Höfling, Sven; Indjin, D.; Vukmirović, Nenad; Ikonić, Z.; Harrison, P.; Reithmaier, J.P.; Forchel, A.

doi:10.1063/1.2194312

Cited by 49 publications

(45 citation statements)

References 54 publications

(64 reference statements)

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“…Our simulation results reproduce the experimentally observed variations in threshold current, THz power, and cut-off currents and predict a currentdependent variation in modulation bandwidth, which accords with the general expectation that modulation bandwidth increases with internal photon density. 12 Our method is a three-stage process: (1) the Schr€ odinger and Poisson equations are solved self-consistently with a full RE model of the system that includes all relevant scattering mechanisms 13 and this is used to deduce the RRE parameters, i.e., ULL and LLL lifetimes, scattering rates between them, injection efficiencies, and gain factor at a range of temperatures and biases; (2) a polynomial function of T and V is fitted to each parameter, thereby producing closed form expressions for inclusion in a RRE model; and (3) the RRE model is solved to obtain carrier and photon populations, using current and ambient (cold finger) temperature as inputs. Stages (1) and (2) are one-off processes that yield a model for a given device and its physical structure.…”

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confidence: 99%

Efficient prediction of terahertz quantum cascade laser dynamics from steady-state simulations

Agnew

Grier

Taimre

et al. 2015

Applied Physics Letters

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Terahertz-frequency quantum cascade lasers (THz QCLs) based on bound-to-continuum active regions are difficult to model owing to their large number of quantum states. We present a computationally efficient reduced rate equation (RE) model that reproduces the experimentally observed variation of THz power with respect to drive current and heat-sink temperature. We also present dynamic (time-domain) simulations under a range of drive currents and predict an increase in modulation bandwidth as the current approaches the peak of the light–current curve, as observed experimentally in mid-infrared QCLs. We account for temperature and bias dependence of the carrier lifetimes, gain, and injection efficiency, calculated from a full rate equation model. The temperature dependence of the simulated threshold current, emitted power, and cut-off current are thus all reproduced accurately with only one fitting parameter, the interface roughness, in the full REs. We propose that the model could therefore be used for rapid dynamical simulation of QCL designs.

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confidence: 99%

Efficient prediction of terahertz quantum cascade laser dynamics from steady-state simulations

Agnew

Grier

Taimre

et al. 2015

Applied Physics Letters

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“…Since the number of total scattering rate processes equals to N 2 (2P þ 1) À N, in order to reduce the number of scattering rate processes necessary to calculate the electron distribution, we have introduced the "tight-binding" approximation 30 assuming that only the nearest neighbours interact, and set P ¼ 2.…”

Section: B the Self-consistent Rate Equation Modelmentioning

confidence: 99%

Genetic algorithm applied to the optimization of quantum cascade lasers with second harmonic generation

Gajic

Radovanović

Milanović

et al. 2014

Journal of Applied Physics

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A computational model for the optimization of the second order optical nonlinearities in GaInAs/AlInAs quantum cascade laser structures is presented. The set of structure parameters that lead to improved device performance was obtained through the implementation of the Genetic Algorithm. In the following step, the linear and second harmonic generation power were calculated by self-consistently solving the system of rate equations for carriers and photons. This rate equation system included both stimulated and simultaneous double photon absorption processes that occur between the levels relevant for second harmonic generation, and material-dependent effective mass, as well as band nonparabolicity, were taken into account. The developed method is general, in the sense that it can be applied to any higher order effect, which requires the photon density equation to be included. Specifically, we have addressed the optimization of the active region of a double quantum well In 0.53 Ga 0.47 As/Al 0.48 In 0.52 As structure and presented its output characteristics. V C 2014 AIP Publishing LLC. [http://dx

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“…In a quantum cascade structure both the "intraperiod" and "interperiod" intersuband optical transitions contribute, and the calculation is performed according to the expression given in Ref. 15.…”

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Electron transport in n-doped Si/SiGe quantum cascade structures

Lazić

Ikonić

Milanović

et al. 2007

Journal of Applied Physics

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Article:Lazic, I., Ikonic, Z., Milanovic, V. et An electron transport model in n-Si/SiGe quantum cascade or superlattice structures is described. The model uses the electronic structure calculated within the effective-mass complex-energy framework, separately for perpendicular ͑X z ͒ and in-plane ͑X xy ͒ valleys, the degeneracy of which is lifted by strain, and additionally by size quantization. The transport is then described via scattering between quantized states, using a rate equations approach and tight-binding expansion, taking the coupling with two nearest-neighbor periods. Acoustic phonon, optical phonon, alloy disorder, and interface roughness scattering are taken into account. The calculated current/voltage dependence and gain profiles are presented for two simple superlattice structures.

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Influence of doping density on electron dynamics in GaAs∕AlGaAs quantum cascade lasers

Cited by 49 publications

References 54 publications

Efficient prediction of terahertz quantum cascade laser dynamics from steady-state simulations

Efficient prediction of terahertz quantum cascade laser dynamics from steady-state simulations

Genetic algorithm applied to the optimization of quantum cascade lasers with second harmonic generation

Electron transport in n-doped Si/SiGe quantum cascade structures

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