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dc.contributor.advisorPackard, Corinne E.
dc.contributor.authorSweet, Cassi A.
dc.date.accessioned2016-02-11T16:07:42Z
dc.date.accessioned2022-02-03T12:57:26Z
dc.date.available2016-02-11T16:07:42Z
dc.date.available2022-02-03T12:57:26Z
dc.date.issued2016
dc.identifierT 7967
dc.identifier.urihttps://hdl.handle.net/11124/170030
dc.description2016 Spring.
dc.descriptionIncludes illustrations (some color).
dc.descriptionIncludes bibliographical references.
dc.description.abstractRecord-high conversion efficiencies inherent in III-V solar cells make them ideal for one-sun photovoltaic applications. However, material costs associated with implementation prevent competitive standing with other solar technologies. This dissertation explores controlled exfoliation of III-V single junction photovoltaic devices from (100) GaAs substrates by spalling to enable wafer reuse for material cost reductions. Spalling is a type of fracture that occurs within the substrate of a bilayer under sufficient misfit stress. A spalling crack propagates parallel to the film/substrate interface at a steady-state spalling depth within the substrate. Spalling in (100) GaAs, a semiconductor with anisotropic fracture properties, presents unique challenges. Orientation of the cleavage plane is not parallel to the steady-state spalling depth which results in a faceted fracture surface. A model is developed by modifying Suo and Hutchinson's spalling mechanics to approximate quantitatively the spalling process parameter window and the thickness of the exfoliated film, i.e. spalling depth, for use with (100) GaAs and other semiconductor materials. Experimental data for faceted (100)-GaAs spalling is shown to be in agreement with this model. A faceted surface leads to undesirable waste material for low cost application to the solar industry. Therefore, methods to mitigate the facet size are explored. Trends in facet size and distribution are linked with both the stressor film deposition parameters and the spalling pull velocity. A spalling fracture is a high energy process where damage to the exfoliated material is a concern. Spalled material quality is assessed directly by dislocation density analysis and indirectly by characterization of electrical performance of high quality spalled photovoltaic devices sensitive to material damage such as dislocation and microcrack occurrence. Controlled application of spalling in (100) GaAs is achieved by exfoliation of a high performance single junction solar cell resulting in 18.2\% conversion efficiency without the use of an anti-reflective coating. It is shown that spalling in (100) GaAs is a successful device exfoliation process that does not generate defects or cause degradation to device performance.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado School of Mines. Arthur Lakes Library
dc.relation.ispartof2016 - Mines Theses & Dissertations
dc.rightsCopyright of the original work is retained by the author.
dc.subjectGaAs fracture
dc.subjectlift-off
dc.subjectsemiconductor
dc.subjectsolar
dc.subjectspalling
dc.subjectwafer reuse
dc.titleSpalling fracture behavior in (100) gallium arsenide
dc.typeText
dc.contributor.committeememberReimanis, Ivar E. (Ivar Edmund)
dc.contributor.committeememberGorman, Brian P.
dc.contributor.committeememberOhno, Timothy R.
dc.contributor.committeememberYoung, David L. (David Levi)
thesis.degree.nameDoctor of Philosophy (Ph.D.)
thesis.degree.levelDoctoral
thesis.degree.disciplineMetallurgical and Materials Engineering
thesis.degree.grantorColorado School of Mines


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