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Highly Efficient Long-Wavelength Infrared, Step-Taper Active-Region Quantum Cascade Lasers.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Highly Efficient Long-Wavelength Infrared, Step-Taper Active-Region Quantum Cascade Lasers./
作者:	Oresick, Kevin.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2021,
面頁冊數:	165 p.
附註:	Source: Dissertations Abstracts International, Volume: 83-01, Section: B.
Contained By:	Dissertations Abstracts International83-01B.
標題:	Applied physics. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28547493
ISBN:	9798516930898

Highly Efficient Long-Wavelength Infrared, Step-Taper Active-Region Quantum Cascade Lasers.
Oresick, Kevin.

Highly Efficient Long-Wavelength Infrared, Step-Taper Active-Region Quantum Cascade Lasers. - Ann Arbor : ProQuest Dissertations & Theses, 2021 - 165 p.

Source: Dissertations Abstracts International, Volume: 83-01, Section: B.

Thesis (Ph.D.)--The University of Wisconsin - Madison, 2021.

This item must not be sold to any third party vendors.

Quantum cascade lasers (QCLs) are semiconductor lasers that emit in the mid- to far-infrared and employ intersubband transitions in multiple quantum-well structures. Conventionally, the active region of QCLs has consisted of quantum wells and barriers of fixed-alloy composition. That has led to severe carrier leakage from the upper-laser level and injector states, evidenced by strong temperature dependences of the device characteristics, which resulted in low values for wall-plug efficiency ηwp of CW-operating devices. We have devised in the past means for carrier-leakage suppression, and have recently derived a comprehensive carrier-leakage formalism that bridges the gap between theoretical and experimental values for the internal efficiency. Here we present a refinement of the comprehensive carrier-leakage formalism and employ it for comparing our band-engineered ~8 μm-emitting QCL, so-called step-tapered active-region (STA), to a conventional ~8 μm-emitting QCL. We find that the internal efficiency reaches a high value of ~73.6%, due to record-high injection- and laser-transition efficiencies. Experimentally we obtain a single-facet ηwp value of 10.6%, a record-high value for 8-11 μm-emitting QCLs grown by MOCVD. Then, by using both band- and interface-roughness (IFR)-scattering - engineering we designed an optimized 8.2 μm-emitting STA-QCL that reaches a record-high injection efficiency of 89.5%. By minimizing the waveguide loss and raising the doping level the device reaches a record-high internal efficiency (80%) for ~8 μm-emitting QCLs as well as a projected ηwp value of 11.2%. The studies are extended to devices of higher layer-interface quality, grown by two different techniques. As a result, we obtain ηwp values as high as 15.6 %. In addition, the optimized STA-QCL has a lower-level lifetime dominated by IFR scattering, which makes it amenable to further optimization via IFR engineering. Finally, we analyze an ~8 μm-emitting QCLs that holds the world record ηwp value, primarily due to low voltages via the realization of photon-induced carrier transport. We find that the device has significant carrier leakage, and show that our optimized STA QCL can reach comparable ηwp values if high-quality interfaces are employed. We then derive ultimate limits for the ηwp value in the 7-11 μm wavelength range.

ISBN: 9798516930898Subjects--Topical Terms:

3343996
Applied physics.
Subjects--Index Terms:

Band engineering

Highly Efficient Long-Wavelength Infrared, Step-Taper Active-Region Quantum Cascade Lasers.
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300 $a 165 p.
500 $a Source: Dissertations Abstracts International, Volume: 83-01, Section: B.
500 $a Advisor: Botez, Dan;Mawst, Luke.
502 $a Thesis (Ph.D.)--The University of Wisconsin - Madison, 2021.
506 $a This item must not be sold to any third party vendors.
520 $a Quantum cascade lasers (QCLs) are semiconductor lasers that emit in the mid- to far-infrared and employ intersubband transitions in multiple quantum-well structures. Conventionally, the active region of QCLs has consisted of quantum wells and barriers of fixed-alloy composition. That has led to severe carrier leakage from the upper-laser level and injector states, evidenced by strong temperature dependences of the device characteristics, which resulted in low values for wall-plug efficiency ηwp of CW-operating devices. We have devised in the past means for carrier-leakage suppression, and have recently derived a comprehensive carrier-leakage formalism that bridges the gap between theoretical and experimental values for the internal efficiency. Here we present a refinement of the comprehensive carrier-leakage formalism and employ it for comparing our band-engineered ~8 μm-emitting QCL, so-called step-tapered active-region (STA), to a conventional ~8 μm-emitting QCL. We find that the internal efficiency reaches a high value of ~73.6%, due to record-high injection- and laser-transition efficiencies. Experimentally we obtain a single-facet ηwp value of 10.6%, a record-high value for 8-11 μm-emitting QCLs grown by MOCVD. Then, by using both band- and interface-roughness (IFR)-scattering - engineering we designed an optimized 8.2 μm-emitting STA-QCL that reaches a record-high injection efficiency of 89.5%. By minimizing the waveguide loss and raising the doping level the device reaches a record-high internal efficiency (80%) for ~8 μm-emitting QCLs as well as a projected ηwp value of 11.2%. The studies are extended to devices of higher layer-interface quality, grown by two different techniques. As a result, we obtain ηwp values as high as 15.6 %. In addition, the optimized STA-QCL has a lower-level lifetime dominated by IFR scattering, which makes it amenable to further optimization via IFR engineering. Finally, we analyze an ~8 μm-emitting QCLs that holds the world record ηwp value, primarily due to low voltages via the realization of photon-induced carrier transport. We find that the device has significant carrier leakage, and show that our optimized STA QCL can reach comparable ηwp values if high-quality interfaces are employed. We then derive ultimate limits for the ηwp value in the 7-11 μm wavelength range.
590 $a School code: 0262.
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650 4 $a Electrical engineering. $3 649834
650 4 $a Materials science. $3 543314
653 $a Band engineering
653 $a Carrier leakage
653 $a High power lasers
653 $a Internal efficiency
653 $a Quantum cascade lasers
653 $a Wall plug efficiency
690 $a 0215
690 $a 0544
690 $a 0794
710 2 $a The University of Wisconsin - Madison. $b Electrical Engineering. $3 2095968
773 0 $t Dissertations Abstracts International $g 83-01B.
790 $a 0262
791 $a Ph.D.
792 $a 2021
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28547493