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dc.contributor.advisorStradins, Paul
dc.contributor.advisorAgarwal, Sumit
dc.contributor.authorAnderson, Caroline L.
dc.date.accessioned2023-12-12T19:27:00Z
dc.date.available2023-12-12T19:27:00Z
dc.date.issued2023
dc.identifierAnderson_mines_0052E_12713.pdf
dc.identifierT 9634
dc.identifier.urihttps://hdl.handle.net/11124/178665
dc.descriptionIncludes bibliographical references.
dc.description2023 Summer.
dc.description.abstractPolycrystalline Si (poly-Si) passivating contact solar cells are emerging as a leading technology in the solar photovoltaic (PV) market. Currently, their deployment is limited to electron-selective contacts on planar surface morphology: this is due to inferior performance of hole-selective poly-Si contacts and poly-Si contacts fabricated on alkaline-textured Si surfaces. Overcoming these limitations could foster broader adoption of poly-Si contact technology. A dielectric interlayer between poly-Si and c-Si is required to mitigate defects at the poly-Si/c-Si interface. Current transport through the dielectric occurs preferentially via direct quantum tunneling, or via discontinuities in the dielectric layer, known as “nanopinholes”. This thesis investigates pinhole-dependent poly-Si passivating contacts and focuses on parameters that control the area density of pinholes. Due to the defective nature of pinholes, tuning pinhole area density is crucial in the optimization of poly-Si contacts. In Chapter 3, the effect of surface morphology on thermal pinhole creation is investigated for poly-Si/SiOx on various textured morphologies. The formation of pinholes in the insulating SiOx layer is induced through thermal processing at temperatures exceeding 1000 ◦C. The findings reveal that textured morphologies exhibit higher susceptibility to pinhole formation compared to planar morphology. Notably, a thermal process capable of selectively creating pinholes at the vertices of inverted pyramid-textured c-Si is identified. In Chapters 4 and 5, a fabrication process is developed for the creation of pinholes at room temperature. This process utilizes galvanic corrosion principles within a wet chemical environment to selectively etch the dielectric interlayer, resulting in the formation of pinholes with widths ranging from ≈10 to 200 nm. Extensive electrical and microscopic investigations reveal that the presence of etch undercut in the dielectric layer leads to the development of electrically resistive pinholes. However, through the implementation of a modified processing sequence that eliminates undercut, conductive pinholes are successfully fabricated. Moreover, the density of pinholes can be finely controlled by adjusting the concentration of the etching solution, offering manipulation within a broad range of approximately 1×10^4 to 5×10^7 cm^(−2). The application of this innovative technique in fabricating hole-selective poly-Si/SiNy/SiOx contacts on both textured and planar c-Si substrates demonstrates excellent hole selectivity, with J_0 <1 fA/cm^2 and ρ_c <30 mΩ·cm^2. Finally, the integration of this process into the fabrication of single-junction single-side textured Czochralski Si solar cells resulted in open circuit voltage of 729.0 mV and a fill factor of 81.9%.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado School of Mines. Arthur Lakes Library
dc.relation.ispartof2023 - Mines Theses & Dissertations
dc.rightsCopyright of the original work is retained by the author.
dc.subjectEBIC
dc.subjectMACE
dc.subjectpinholes
dc.subjectPOLO
dc.subjectpoly-Si
dc.subjectSi solar cell
dc.titlePinhole-dependent polycrystalline silicon contacts for high-efficiency Czochralski silicon solar cells
dc.typeText
dc.date.updated2023-11-30T05:09:25Z
dc.contributor.committeememberSingh, Meenakshi
dc.contributor.committeememberGómez-Gualdrón, Diego A.
dc.contributor.committeememberWolden, Colin Andrew
thesis.degree.nameDoctor of Philosophy (Ph.D.)
thesis.degree.levelDoctoral
thesis.degree.disciplineChemical and Biological Engineering
thesis.degree.grantorColorado School of Mines


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