High internal differential efficiency mid-infrared quantum cascade lasers

Botez, D.; Kirch, Jeremy; Chang, Chin‐Chen; Boyle, Colin; Kim, Honghyuk; Oresick, K.; Sigler, C.; Mawst, Luke J.; Jo, Minhyeok; Shin, Jae Cheol; Doo, Gun-Kim; Lindberg, D.; Earles, T.

doi:10.1117/12.2249537

Cited by 6 publications

(2 citation statements)

References 38 publications

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“…Quantum cascade laser (QCL) devices employ conduction band engineering to obtain a desired emission wavelength. Typically, they contain active regions consisting of 30-40 repetitions of a complex motif composed of quantum wells and barriers of various compositions and thicknesses in the range of 1-5 nm each [1]. A desirable feature of QCLs, being intersubband transition devices, is the tunability of the emission wavelength through the design of the thickness and composition of each layer within a chosen material system.…”

Section: Introductionmentioning

confidence: 99%

Interfacial Mixing Analysis for Strained Layer Superlattices by Atom Probe Tomography

et al. 2018

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Quantum wells and barriers with precise thicknesses and abrupt composition changes at their interfaces are critical for obtaining the desired emission wavelength from quantum cascade laser devices. High-resolution X-ray diffraction and transmission electron microscopy are commonly used to calibrate and characterize the layers’ thicknesses and compositions. A complementary technique, atom probe tomography, was employed here to obtain a direct measurement of the 3-dimensional spatially-resolved compositional profile in two InxGa1−xAs/InyAl1−yAs III-V strained-layer superlattice structures, both grown at 605 °C. Fitting the measured composition profiles to solutions to Fick’s Second Law yielded an average interdiffusion coefficient of 3.5 × 10−23 m2 s−1 at 605 °C. The extent of interdiffusion into each layer determined for these specific superlattices was 0.55 nm on average. The results suggest that quaternary active layers will form, rather than the intended ternary compounds, in structures with thicknesses and growth protocols that are typically designed for quantum cascade laser devices.

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Section: Introductionmentioning

confidence: 99%

Interfacial Mixing Analysis for Strained Layer Superlattices by Atom Probe Tomography

et al. 2018

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“…In the current work, we investigate the use of MOCVD for both the growth of the MBL and the QCL on a (001) Si substrate. InP MBLs with InAs/InP QD insertions are used as virtual substrates for the growth of a QCL with a step‐tapered active‐resonant extraction design for ≈4.8 µm emission wavelength . The insertions are two repetitions of seven‐layer InAs/InP QDs separated by a 300 nm spacer layer of InP, which act as dislocation filters (DFL) .…”

Section: Introductionmentioning

confidence: 99%

III-V Superlattices on InP/Si Metamorphic Buffer Layers for λ ≈4.8 μm Quantum Cascade Lasers

Rajeev

Shi

et al. 2018

Phys. Status Solidi A

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Metalorganic chemical vapor deposition (MOCVD) growth of InP-based quantum cascade laser (QCL) structures on a Si (001) substrate is demonstrated by employing a metamorphic InP buffer layer with InAs/InP quantum dots as dislocation filters. Calibration samples consist of a strain-compensated 11.98 nm In 0.365 Al 0.635 As/14.8 nm In 0.64 Ga 0.36 As superlattice (SL) structure as well as 5-stages of the λ % 4.8 mm QCL active region, which are grown atop the metamorphic buffer and are used to assess the structural properties of the SL through high-resolution X-ray diffraction and high-resolution transmission electron microscopy. Full QCL structures with 40-stage active region are fabricated into edge-emitting ridge-waveguide structures and demonstrate low temperature electroluminescence with a FWHM of 48.6 meV.

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Carrier leakage via interface-roughness scattering bridges gap between theoretical and experimental internal efficiencies of quantum cascade lasers

Boyle

Oresick

Kirch

et al. 2020

Applied Physics Letters

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When conventionally calculating carrier leakage for state-of-the-art quantum cascade lasers (QCLs), that is, LO-phonon-assisted leakage from the upper laser level via electron thermal excitation to high-energy active-region (AR) states, followed by relaxation to low-energy AR states, ∼18%-wide gaps were recently found between calculated and experimentally measured internal efficiency values. We incorporate elastic scattering [i.e., interface-roughness (IFR) and alloy-disorder scattering] into the carrier-leakage process and consider carrier leakage from key injector states as well. In addition, the expressions for LO-phonon and IFR-triggered carrier-leakage currents take into account the large percentage of thermally excited electrons that return back to initial states via both inelastic and elastic scattering. As a result, we find that the gaps between theoretical and experimental internal efficiency values are essentially bridged. Another finding is that, for the investigated state-of-the-art structures, IFR scattering causes the total carrier leakage to reach values as much as an order of magnitude higher than conventional inelastic scattering-only leakage. The developed formalism opens the way to significantly increase the internal efficiency (i.e., to more than 80%) via IFR-scattering engineering, such that maximum wall-plug efficiencies close to projected fundamental, both-facets values (e.g., 42% at λ = 4.6 μm) can be achieved. By employing this formalism, we reached a 4.6 μm-emitting-QCL preliminary design for suppressing IFR-triggered carrier leakage, which provides an internal efficiency of 86% as well as a projected single-facet wall-plug efficiency value of 36% at a heatsink temperature of 300 K.

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High internal differential efficiency mid-infrared quantum cascade lasers

Cited by 6 publications

References 38 publications

Interfacial Mixing Analysis for Strained Layer Superlattices by Atom Probe Tomography

Interfacial Mixing Analysis for Strained Layer Superlattices by Atom Probe Tomography

III-V Superlattices on InP/Si Metamorphic Buffer Layers for λ ≈4.8 μm Quantum Cascade Lasers

Carrier leakage via interface-roughness scattering bridges gap between theoretical and experimental internal efficiencies of quantum cascade lasers

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