{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/97503"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/97503","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Spectroscopic ellipsometry and dielectric modeling of thin film CdTe/CdS photovoltaic devices","abstract":"Spectroscopic ellipsometry (SE) is a non-contact, non-destructive characterization technique for probing the optical properties of thin films. With the advent of second-generation solar cells, SE has seen use as a method for determining the dielectric function of each layer in heterostructured, thin-film photovoltaic devices. The aim of this thesis is to assess the capability of SE to resolve changes associated with illumination in the dielectric function of the absorbing layer of CdTe/CdS photovoltaic devices. Subsequently, this thesis aims to model the dielectric function of CdTe using critical point parabolic band theory (CPPB) and map the observed modulation to changes in the band structure associated with the photoexcitation of carriers. SE successfully measured the absolute geometry and optical properties of the solar cell, with the parameterization of the absorbing layer corroborating previous research. Small, qualitatively reproducible changes in the raw SE spectra were observed when the device was subject to illumination. Nevertheless, the associated modulation of the dielectric function was too small in comparison to the uncertainty to be of scientific use. Although SE proved unable to resolve the desired modulation, improvements in experimental methodology may allow for greater success in future work.","abstract_html":"Spectroscopic ellipsometry (SE) is a non-contact, non-destructive characterization technique for probing the optical properties of thin films. With the advent of second-generation solar cells, SE has seen use as a method for determining the dielectric function of each layer in heterostructured, thin-film photovoltaic devices. The aim of this thesis is to assess the capability of SE to resolve changes associated with illumination in the dielectric function of the absorbing layer of CdTe/CdS photovoltaic devices. Subsequently, this thesis aims to model the dielectric function of CdTe using critical point parabolic band theory (CPPB) and map the observed modulation to changes in the band structure associated with the photoexcitation of carriers. SE successfully measured the absolute geometry and optical properties of the solar cell, with the parameterization of the absorbing layer corroborating previous research. Small, qualitatively reproducible changes in the raw SE spectra were observed when the device was subject to illumination. Nevertheless, the associated modulation of the dielectric function was too small in comparison to the uncertainty to be of scientific use. Although SE proved unable to resolve the desired modulation, improvements in experimental methodology may allow for greater success in future work.","abstract_has_math":false,"creators":["Darrow, Michael Cole"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Materials Science and Engineering","degree_department":null,"school":null,"contributors":["Rockett, Angus A."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2017,"date_issued":"2017-08-10T19:16:18Z","date_published":"2017-08-10T19:16:18Z","updated_at":"2026-07-22T22:24:34Z","subjects":["Ellipsometry","Cadmium telluride (CdTe)","Dielectric modeling","Photovoltaics"],"languages":["en"],"rights":["Copyright 2017 Michael Darrow"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/97503","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Rockett, Angus A."]},{"key":"dc:creator","label":"Author","values":["Darrow, Michael Cole"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2017-08-10T19:16:18Z","2017-04-28","2017-05"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Materials Science and Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"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":["Ellipsometry","Cadmium telluride (CdTe)","Dielectric modeling","Photovoltaics"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2017 Michael Darrow"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/97503"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Spectroscopic ellipsometry (SE) is a non-contact, non-destructive characterization technique for probing the optical properties of thin films. With the advent of second-generation solar cells, SE has seen use as a method for determining the dielectric function of each layer in heterostructured, thin-film photovoltaic devices. The aim of this thesis is to assess the capability of SE to resolve changes associated with illumination in the dielectric function of the absorbing layer of CdTe/CdS photovoltaic devices. Subsequently, this thesis aims to model the dielectric function of CdTe using critical point parabolic band theory (CPPB) and map the observed modulation to changes in the band structure associated with the photoexcitation of carriers. SE successfully measured the absolute geometry and optical properties of the solar cell, with the parameterization of the absorbing layer corroborating previous research. Small, qualitatively reproducible changes in the raw SE spectra were observed when the device was subject to illumination. Nevertheless, the associated modulation of the dielectric function was too small in comparison to the uncertainty to be of scientific use. Although SE proved unable to resolve the desired modulation, improvements in experimental methodology may allow for greater success in future work.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2017-08-10 without embargo terms","The student, Michael Darrow, accepted the attached license on 2017-04-26 at 21:53.","The student, Michael Darrow, submitted this Thesis for approval on 2017-04-27 at 14:09.","This Thesis was approved for publication on 2017-04-28 at 12:45.","DSpace SAF Submission Ingestion Package generated from Vireo submission #11106 on 2017-08-10 at 13:46:53","Made available in DSpace on 2017-08-10T19:16:18Z (GMT). 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The aim of this thesis is to assess the capability of SE to resolve changes associated with illumination in the dielectric function of the absorbing layer of CdTe/CdS photovoltaic devices. Subsequently, this thesis aims to model the dielectric function of CdTe using critical point parabolic band theory (CPPB) and map the observed modulation to changes in the band structure associated with the photoexcitation of carriers. SE successfully measured the absolute geometry and optical properties of the solar cell, with the parameterization of the absorbing layer corroborating previous research. Small, qualitatively reproducible changes in the raw SE spectra were observed when the device was subject to illumination. Nevertheless, the associated modulation of the dielectric function was too small in comparison to the uncertainty to be of scientific use. Although SE proved unable to resolve the desired modulation, improvements in experimental methodology may allow for greater success in future work.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2017-08-10 without embargo terms","The student, Michael Darrow, accepted the attached license on 2017-04-26 at 21:53.","The student, Michael Darrow, submitted this Thesis for approval on 2017-04-27 at 14:09.","This Thesis was approved for publication on 2017-04-28 at 12:45.","DSpace SAF Submission Ingestion Package generated from Vireo submission #11106 on 2017-08-10 at 13:46:53","Made available in DSpace on 2017-08-10T19:16:18Z (GMT). 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