{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/129761"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/129761","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Epitaxial design, fabrication development, and characterization of transistor-injected quantum cascade laser structures","abstract":"Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-05-01","abstract_html":"Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-05-01","abstract_has_math":false,"creators":["Kaufman, Robert Bruce"],"institution":"University of Illinois Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Electrical & Computer Engr","degree_department":null,"school":null,"contributors":["Dallesasse, John M","Lee, Minjoo","Bayram, Can","Nahrstedt, Klara"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025-05-01","date_published":"2025-05-01","updated_at":"2026-07-22T22:25:05Z","subjects":["quantum cascade laser","transistor laser","midwave infrared"],"languages":["en","eng"],"rights":["Copyright 2025 Robert Bruce Kaufman"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/129761","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Dallesasse, John M","Lee, Minjoo","Bayram, Can","Nahrstedt, Klara"]},{"key":"dc:creator","label":"Author","values":["Kaufman, Robert Bruce"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2025-05-01","2025-05"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Electrical & Computer Engr"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["quantum cascade laser","transistor laser","midwave infrared"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en","eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2025 Robert Bruce Kaufman"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/129761"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-05-01","The student, Robert Kaufman, accepted the attached license on 2025-04-30 at 13:22.","The student, Robert Kaufman, submitted this Dissertation for approval on 2025-04-30 at 13:34.","This Dissertation was approved for publication on 2025-05-01 at 11:05.","DSpace SAF Submission Ingestion Package generated from Vireo submission #22120 on 2025-10-19 at 19:54:50","Mid-wave infrared (MWIR) and long-wave infrared (LWIR) coherent optical sources are garnering attention for their role in facilitating compact solutions to a range of important fields, such as spectroscopy, remote chemical sensing, and free-space optical communication systems. While the quantum cascade laser (QCL) presents one appealing solution for these infrared sources, inherent limitations related to its unipolar nature dictate the optical power (controlled by the current) and emission wavelength (controlled by active region bias) are inherently linked. The transistor-injected quantum cascade laser (TI-QCL) presents a novel three-terminal QCL design that seeks to address these limitations in order to provide a more controllable and efficient solution to the MWIR and LWIR problem space. By placing the cascaded active region within the base-collector space charge region of a heterojunction bipolar transistor (HBT), independent control of injection current and active-region bias is achievable. To progress the TI-QCL device concept closer to demonstration, efforts are taken in three domains: epitaxial design, fabrication process optimization, and sample characterization. In this work, the overall fabrication process for QCL and TI-QCL devices is presented along with the development efforts used to improve device performance including, among other efforts, ridge guide formation, lateral carrier isolation methods, and high-reflective facet coatings. These fabrication processes are used to create samples from two different epitaxial designs: the 3rd and 4th generation TI-QCL structures, both on InP substrates. The 3rd generation TI-QCL design targets an 8.3 μm emission whereas the 4th generation design targets 4.7 μm. Novel characterization results for the 3rd generation TI-QCL are demonstrated at 77 K, including negative differential collector current, self-oscillations in collector current, 1.58 μm short-wave infrared (SWIR) spontaneous emission, SWIIR lasing, and the first detected MWIR emission from a transistor-injected quantum cascade structure. Extended modeling capabilities are developed to better understand the quantum states in the active region, the carrier transport at the interface, and the performance of the optical mode. In addition, a depletion-approximation model is made for the TI-QCL to understand the field distribution at different bias and current conditions in the base-collector junction. These new insights are utilized to optimize the design of the 4th generation epitaxial material which includes a doped active region variant, an unintentionally-doped active region variant, and a standard QCL variant. Promising early electroluminescence and room-temperature electrical characterization results for this material are presented and analyzed using the depletion model. Future targets for optical characterization of the new material and potential future applications for a working TI-QCL device are discussed."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Epitaxial design, fabrication development, and characterization of transistor-injected quantum cascade laser structures"]}]}],"canonical_facts":{"dc:contributor":["Dallesasse, John M","Lee, Minjoo","Bayram, Can","Nahrstedt, Klara"],"dc:creator":["Kaufman, Robert Bruce"],"dc:date":["2025-05-01","2025-05"],"dc:description":["Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-05-01","The student, Robert Kaufman, accepted the attached license on 2025-04-30 at 13:22.","The student, Robert Kaufman, submitted this Dissertation for approval on 2025-04-30 at 13:34.","This Dissertation was approved for publication on 2025-05-01 at 11:05.","DSpace SAF Submission Ingestion Package generated from Vireo submission #22120 on 2025-10-19 at 19:54:50","Mid-wave infrared (MWIR) and long-wave infrared (LWIR) coherent optical sources are garnering attention for their role in facilitating compact solutions to a range of important fields, such as spectroscopy, remote chemical sensing, and free-space optical communication systems. While the quantum cascade laser (QCL) presents one appealing solution for these infrared sources, inherent limitations related to its unipolar nature dictate the optical power (controlled by the current) and emission wavelength (controlled by active region bias) are inherently linked. The transistor-injected quantum cascade laser (TI-QCL) presents a novel three-terminal QCL design that seeks to address these limitations in order to provide a more controllable and efficient solution to the MWIR and LWIR problem space. By placing the cascaded active region within the base-collector space charge region of a heterojunction bipolar transistor (HBT), independent control of injection current and active-region bias is achievable. To progress the TI-QCL device concept closer to demonstration, efforts are taken in three domains: epitaxial design, fabrication process optimization, and sample characterization. In this work, the overall fabrication process for QCL and TI-QCL devices is presented along with the development efforts used to improve device performance including, among other efforts, ridge guide formation, lateral carrier isolation methods, and high-reflective facet coatings. These fabrication processes are used to create samples from two different epitaxial designs: the 3rd and 4th generation TI-QCL structures, both on InP substrates. The 3rd generation TI-QCL design targets an 8.3 μm emission whereas the 4th generation design targets 4.7 μm. Novel characterization results for the 3rd generation TI-QCL are demonstrated at 77 K, including negative differential collector current, self-oscillations in collector current, 1.58 μm short-wave infrared (SWIR) spontaneous emission, SWIIR lasing, and the first detected MWIR emission from a transistor-injected quantum cascade structure. Extended modeling capabilities are developed to better understand the quantum states in the active region, the carrier transport at the interface, and the performance of the optical mode. In addition, a depletion-approximation model is made for the TI-QCL to understand the field distribution at different bias and current conditions in the base-collector junction. These new insights are utilized to optimize the design of the 4th generation epitaxial material which includes a doped active region variant, an unintentionally-doped active region variant, and a standard QCL variant. Promising early electroluminescence and room-temperature electrical characterization results for this material are presented and analyzed using the depletion model. Future targets for optical characterization of the new material and potential future applications for a working TI-QCL device are discussed."],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/129761"],"dc:language":["en","eng"],"dc:rights":["Copyright 2025 Robert Bruce Kaufman"],"dc:subject":["quantum cascade laser","transistor laser","midwave infrared"],"dc:title":["Epitaxial design, fabrication development, and characterization of transistor-injected quantum cascade laser structures"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Electrical & Computer Engr"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:05Z"}