The Effect of Doping in Split-Well Direct-Phonon THz Quantum-Cascade Laser Structures
We have studied the effect of doping on the temperature performance of a split-well (SW) direct-phonon (DP) terahertz (THz) quantum-cascade laser (QCL) scheme supporting a clean three-level system. Achieving a system that is as close as possible to a clean n-level system proved to be the strategy th...
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MDPI AG
2021-05-01
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| Series: | Photonics |
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| Online Access: | https://www.mdpi.com/2304-6732/8/6/195 |
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| author | Nathalie Lander Gower Silvia Piperno Asaf Albo |
| author_facet | Nathalie Lander Gower Silvia Piperno Asaf Albo |
| author_sort | Nathalie Lander Gower |
| collection | DOAJ |
| description | We have studied the effect of doping on the temperature performance of a split-well (SW) direct-phonon (DP) terahertz (THz) quantum-cascade laser (QCL) scheme supporting a clean three-level system. Achieving a system that is as close as possible to a clean n-level system proved to be the strategy that led to the best temperature performance in THz-QCLs. We expected to obtain a similar improvement to that observed in resonant-phonon (RP) schemes after increasing the carrier concentration from 3 × <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mn>10</mn></mrow><mrow><mn>10</mn></mrow></msup><msup><mrow><mrow><mo> </mo><mi>cm</mi></mrow></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></mrow></semantics></math></inline-formula> to 6 × <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mn>10</mn></mrow><mrow><mn>10</mn></mrow></msup><msup><mrow><mrow><mo> </mo><mi>cm</mi></mrow></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></mrow></semantics></math></inline-formula>. Our goal was to improve the temperature performance by increasing the doping, ideally the results should have improved. To our surprise, in the devices we checked, the results show the contrary. Although an increase in doping had previously shown a positive effect in RP schemes, our results indicated that this does not happen with SW–DP devices. However, we observed a significant increase in gain broadening and a reduction in the dephasing time as the doping and temperature increased. We attribute these effects to enhanced ionized-impurity scattering (IIS). The observation and study of effects related to dephasing included in our experimental work have previously only been possible via simulation. |
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| language | English |
| last_indexed | 2024-03-10T10:51:09Z |
| publishDate | 2021-05-01 |
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| spelling | doaj.art-da1048b0803e45fc958b95bec44938172023-11-21T22:13:38ZengMDPI AGPhotonics2304-67322021-05-018619510.3390/photonics8060195The Effect of Doping in Split-Well Direct-Phonon THz Quantum-Cascade Laser StructuresNathalie Lander Gower0Silvia Piperno1Asaf Albo2Faculty of Engineering, Bar-Ilan University, Ramat Gan 5290002, IsraelFaculty of Engineering, Bar-Ilan University, Ramat Gan 5290002, IsraelFaculty of Engineering, Bar-Ilan University, Ramat Gan 5290002, IsraelWe have studied the effect of doping on the temperature performance of a split-well (SW) direct-phonon (DP) terahertz (THz) quantum-cascade laser (QCL) scheme supporting a clean three-level system. Achieving a system that is as close as possible to a clean n-level system proved to be the strategy that led to the best temperature performance in THz-QCLs. We expected to obtain a similar improvement to that observed in resonant-phonon (RP) schemes after increasing the carrier concentration from 3 × <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mn>10</mn></mrow><mrow><mn>10</mn></mrow></msup><msup><mrow><mrow><mo> </mo><mi>cm</mi></mrow></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></mrow></semantics></math></inline-formula> to 6 × <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mn>10</mn></mrow><mrow><mn>10</mn></mrow></msup><msup><mrow><mrow><mo> </mo><mi>cm</mi></mrow></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></mrow></semantics></math></inline-formula>. Our goal was to improve the temperature performance by increasing the doping, ideally the results should have improved. To our surprise, in the devices we checked, the results show the contrary. Although an increase in doping had previously shown a positive effect in RP schemes, our results indicated that this does not happen with SW–DP devices. However, we observed a significant increase in gain broadening and a reduction in the dephasing time as the doping and temperature increased. We attribute these effects to enhanced ionized-impurity scattering (IIS). The observation and study of effects related to dephasing included in our experimental work have previously only been possible via simulation.https://www.mdpi.com/2304-6732/8/6/195THz-QCLsdoping effectLO-phonon scattering |
| spellingShingle | Nathalie Lander Gower Silvia Piperno Asaf Albo The Effect of Doping in Split-Well Direct-Phonon THz Quantum-Cascade Laser Structures Photonics THz-QCLs doping effect LO-phonon scattering |
| title | The Effect of Doping in Split-Well Direct-Phonon THz Quantum-Cascade Laser Structures |
| title_full | The Effect of Doping in Split-Well Direct-Phonon THz Quantum-Cascade Laser Structures |
| title_fullStr | The Effect of Doping in Split-Well Direct-Phonon THz Quantum-Cascade Laser Structures |
| title_full_unstemmed | The Effect of Doping in Split-Well Direct-Phonon THz Quantum-Cascade Laser Structures |
| title_short | The Effect of Doping in Split-Well Direct-Phonon THz Quantum-Cascade Laser Structures |
| title_sort | effect of doping in split well direct phonon thz quantum cascade laser structures |
| topic | THz-QCLs doping effect LO-phonon scattering |
| url | https://www.mdpi.com/2304-6732/8/6/195 |
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