{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/89175"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/89175","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Characterization of silicon photovoltaic wafers using polarized infrared imaging","abstract":"Photovoltaic (PV) solar industry uses low-cost material processing methods to produce silicon wafer-based solar cells. Thermal process can introduce crystal defects and residual stress in a PV wafer, which can impact the electrical performance and mechanical reliability of a finished solar cell. This research presents characterization methods for mono-crystal and multi-crystal silicon PV wafers, using an integrated polarized infrared imaging tool capable of both photoelastic (PE) and polarized photoluminescence (PL) imaging. Infrared PE imaging is used to investigate the thermal process-induced residual stress and defect-related stress in mono-crystal silicon PV wafers. The measured stress pattern shows that dislocation structures interact with the thermal residual stress, forming slip band structures oriented at 45 degrees to the wafer edges. The measured PE images are then interpreted using a discrete dislocation-based numerical modeling approach that accounts for stress relaxation in the wafer due to the dislocation structures. The model leads to simulated PE images and is used to analyze the preferred dislocation slip band orientations for wafer strain energy reduction. The analysis is consistent with experimental observations, forming the basis for a more quantitative infrared PE-based inspection method. Crystal growth process for multi-crystal silicon PV wafers results in grain boundaries and dislocation structures that impact solar cell performance. These defects are investigated using the polarized PL imaging setup, which can spatially resolve the defect structures from both the band-to-band and defect-related PL emission. The polarization resolving ability allows the identification and the correlation among different defect types. The technology described here creates a pathway to rapid full-field wafer quality inspection in a manufacturing setting, and will help to improve PV wafer material processing.","abstract_html":"Photovoltaic (PV) solar industry uses low-cost material processing methods to produce silicon wafer-based solar cells. Thermal process can introduce crystal defects and residual stress in a PV wafer, which can impact the electrical performance and mechanical reliability of a finished solar cell. This research presents characterization methods for mono-crystal and multi-crystal silicon PV wafers, using an integrated polarized infrared imaging tool capable of both photoelastic (PE) and polarized photoluminescence (PL) imaging. Infrared PE imaging is used to investigate the thermal process-induced residual stress and defect-related stress in mono-crystal silicon PV wafers. The measured stress pattern shows that dislocation structures interact with the thermal residual stress, forming slip band structures oriented at 45 degrees to the wafer edges. The measured PE images are then interpreted using a discrete dislocation-based numerical modeling approach that accounts for stress relaxation in the wafer due to the dislocation structures. The model leads to simulated PE images and is used to analyze the preferred dislocation slip band orientations for wafer strain energy reduction. The analysis is consistent with experimental observations, forming the basis for a more quantitative infrared PE-based inspection method. Crystal growth process for multi-crystal silicon PV wafers results in grain boundaries and dislocation structures that impact solar cell performance. These defects are investigated using the polarized PL imaging setup, which can spatially resolve the defect structures from both the band-to-band and defect-related PL emission. The polarization resolving ability allows the identification and the correlation among different defect types. The technology described here creates a pathway to rapid full-field wafer quality inspection in a manufacturing setting, and will help to improve PV wafer material processing.","abstract_has_math":false,"creators":["Lin, Tung-Wei"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Johnson, Harley T","Horn, Gavin P","Beaudoin, Armand","Ertekin, Elif"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2018,"date_issued":"2018-03-03T10:15:31Z","date_published":"2018-03-03T10:15:31Z","updated_at":"2026-07-22T22:26:32Z","subjects":["photovoltaic","photoluminescence","photoelasticity","dislocation","silicon"],"languages":["en"],"rights":["Copyright 2015 Tung-Wei Lin"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/89175","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Johnson, Harley T","Horn, Gavin P","Beaudoin, Armand","Ertekin, Elif"]},{"key":"dc:creator","label":"Author","values":["Lin, Tung-Wei"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2018-03-03T10:15:31Z","2015-09-22","2015-12","2016-03-02T20:57:22Z"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical Engineering"]},{"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 at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["photovoltaic","photoluminescence","photoelasticity","dislocation","silicon"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2015 Tung-Wei Lin"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/89175"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Photovoltaic (PV) solar industry uses low-cost material processing methods to produce silicon wafer-based solar cells. Thermal process can introduce crystal defects and residual stress in a PV wafer, which can impact the electrical performance and mechanical reliability of a finished solar cell. This research presents characterization methods for mono-crystal and multi-crystal silicon PV wafers, using an integrated polarized infrared imaging tool capable of both photoelastic (PE) and polarized photoluminescence (PL) imaging. Infrared PE imaging is used to investigate the thermal process-induced residual stress and defect-related stress in mono-crystal silicon PV wafers. The measured stress pattern shows that dislocation structures interact with the thermal residual stress, forming slip band structures oriented at 45 degrees to the wafer edges. The measured PE images are then interpreted using a discrete dislocation-based numerical modeling approach that accounts for stress relaxation in the wafer due to the dislocation structures. The model leads to simulated PE images and is used to analyze the preferred dislocation slip band orientations for wafer strain energy reduction. The analysis is consistent with experimental observations, forming the basis for a more quantitative infrared PE-based inspection method. Crystal growth process for multi-crystal silicon PV wafers results in grain boundaries and dislocation structures that impact solar cell performance. These defects are investigated using the polarized PL imaging setup, which can spatially resolve the defect structures from both the band-to-band and defect-related PL emission. The polarization resolving ability allows the identification and the correlation among different defect types. The technology described here creates a pathway to rapid full-field wafer quality inspection in a manufacturing setting, and will help to improve PV wafer material processing.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2017-12-01","The student, Tung-Wei Lin, accepted the attached license on 2015-09-18 at 16:37.","The student, Tung-Wei Lin, submitted this Dissertation for approval on 2015-09-18 at 16:56.","This Dissertation was approved for publication on 2015-09-22 at 08:46.","DSpace SAF Submission Ingestion Package generated from Vireo submission #8693 on 2016-03-02 at 14:12:07","Made available in DSpace on 2016-03-02T20:57:22Z (GMT). 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Thermal process can introduce crystal defects and residual stress in a PV wafer, which can impact the electrical performance and mechanical reliability of a finished solar cell. This research presents characterization methods for mono-crystal and multi-crystal silicon PV wafers, using an integrated polarized infrared imaging tool capable of both photoelastic (PE) and polarized photoluminescence (PL) imaging. Infrared PE imaging is used to investigate the thermal process-induced residual stress and defect-related stress in mono-crystal silicon PV wafers. The measured stress pattern shows that dislocation structures interact with the thermal residual stress, forming slip band structures oriented at 45 degrees to the wafer edges. The measured PE images are then interpreted using a discrete dislocation-based numerical modeling approach that accounts for stress relaxation in the wafer due to the dislocation structures. The model leads to simulated PE images and is used to analyze the preferred dislocation slip band orientations for wafer strain energy reduction. The analysis is consistent with experimental observations, forming the basis for a more quantitative infrared PE-based inspection method. Crystal growth process for multi-crystal silicon PV wafers results in grain boundaries and dislocation structures that impact solar cell performance. These defects are investigated using the polarized PL imaging setup, which can spatially resolve the defect structures from both the band-to-band and defect-related PL emission. The polarization resolving ability allows the identification and the correlation among different defect types. The technology described here creates a pathway to rapid full-field wafer quality inspection in a manufacturing setting, and will help to improve PV wafer material processing.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2017-12-01","The student, Tung-Wei Lin, accepted the attached license on 2015-09-18 at 16:37.","The student, Tung-Wei Lin, submitted this Dissertation for approval on 2015-09-18 at 16:56.","This Dissertation was approved for publication on 2015-09-22 at 08:46.","DSpace SAF Submission Ingestion Package generated from Vireo submission #8693 on 2016-03-02 at 14:12:07","Made available in DSpace on 2016-03-02T20:57:22Z (GMT). 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