{"id":{"repo_id":"mit","oai_identifier":"oai:dspace.mit.edu:1721.1/151894"},"canonical_url":"https://search.dev.ndltd.org/etd/mit/oai:dspace.mit.edu:1721.1/151894","repository":{"repo_id":"mit","name":"MIT","base_url":"https://dspace.mit.edu/oai/request"},"display":{"title":"Layer-by-Layer Single-crystal Two-dimensional Material Growth by Geometric Confinement","abstract":"Two-dimensional (2D) transition metal dichalcogenides (TMDs) and their heterostructures have been widely studied for next-generation electronics. However, the following critical challenges have hindered them from their commercialization: 1) precise layer control during their growth, 2) maintaining single crystallinity at wafer-scale, and 3) inevitable transfer-process to fabricate heterostructure for various next-generation applications such as spintronics, valleytronics, and optoelectronics. This thesis introduces a confined-growth technique that can overcome the aforementioned hurdles simultaneously by introducing a geometric SiO₂ mask that has growth selectivity from the underlying substrate. As micrometer-scale SiO₂ trenches reduce the growth duration substantially, single-domain WSe₂ and MoS₂ arrays are obtained on an arbitrary substrate at wafer-scale by filling the trenches before the second layer of nuclei is introduced, thus enabling layer-by-layer growth without requiring epitaxial seeding. In addition, subsequent MoS₂ growth on the WSe₂ arrays yields MoS₂/WSe₂ heterostructures. Therefore, we for the first time demonstrate single-domain TMDs arrays and their heterostructures at wafer-scale with controllable thickness, which of performances are comparable to that fabricated from TMDs flake. This confined-growth technique not only can overcome key obstacles of 2D materials, but also provide a platform with great potential for next-generation 2D-material-based applications.","abstract_html":"Two-dimensional (2D) transition metal dichalcogenides (TMDs) and their heterostructures have been widely studied for next-generation electronics. However, the following critical challenges have hindered them from their commercialization: 1) precise layer control during their growth, 2) maintaining single crystallinity at wafer-scale, and 3) inevitable transfer-process to fabricate heterostructure for various next-generation applications such as spintronics, valleytronics, and optoelectronics. This thesis introduces a confined-growth technique that can overcome the aforementioned hurdles simultaneously by introducing a geometric SiO₂ mask that has growth selectivity from the underlying substrate. As micrometer-scale SiO₂ trenches reduce the growth duration substantially, single-domain WSe₂ and MoS₂ arrays are obtained on an arbitrary substrate at wafer-scale by filling the trenches before the second layer of nuclei is introduced, thus enabling layer-by-layer growth without requiring epitaxial seeding. In addition, subsequent MoS₂ growth on the WSe₂ arrays yields MoS₂/WSe₂ heterostructures. Therefore, we for the first time demonstrate single-domain TMDs arrays and their heterostructures at wafer-scale with controllable thickness, which of performances are comparable to that fabricated from TMDs flake. This confined-growth technique not only can overcome key obstacles of 2D materials, but also provide a platform with great potential for next-generation 2D-material-based applications.","abstract_has_math":false,"creators":["Lee, Doyoon"],"institution":"Massachusetts Institute of Technology","degree_name":"Master","degree_level":null,"degree_discipline":null,"degree_department":"Massachusetts Institute of Technology. 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However, the following critical challenges have hindered them from their commercialization: 1) precise layer control during their growth, 2) maintaining single crystallinity at wafer-scale, and 3) inevitable transfer-process to fabricate heterostructure for various next-generation applications such as spintronics, valleytronics, and optoelectronics. This thesis introduces a confined-growth technique that can overcome the aforementioned hurdles simultaneously by introducing a geometric SiO₂ mask that has growth selectivity from the underlying substrate. As micrometer-scale SiO₂ trenches reduce the growth duration substantially, single-domain WSe₂ and MoS₂ arrays are obtained on an arbitrary substrate at wafer-scale by filling the trenches before the second layer of nuclei is introduced, thus enabling layer-by-layer growth without requiring epitaxial seeding. In addition, subsequent MoS₂ growth on the WSe₂ arrays yields MoS₂/WSe₂ heterostructures. Therefore, we for the first time demonstrate single-domain TMDs arrays and their heterostructures at wafer-scale with controllable thickness, which of performances are comparable to that fabricated from TMDs flake. This confined-growth technique not only can overcome key obstacles of 2D materials, but also provide a platform with great potential for next-generation 2D-material-based applications."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["S.M."]},{"key":"dc:title","label":"Title","values":["Layer-by-Layer Single-crystal Two-dimensional Material Growth by Geometric Confinement"]}]}],"canonical_facts":{"dc:contributor.advisor":["Kim, Jeehwan"],"dc:contributor.department":["Massachusetts Institute of Technology. Department of Mechanical Engineering"],"dc:creator":["Lee, Doyoon"],"dc:date.accessioned":["2023-08-23T16:17:13Z"],"dc:date.available":["2023-08-23T16:17:13Z"],"dc:date.issued":["2023-06"],"dc:description.abstract":["Two-dimensional (2D) transition metal dichalcogenides (TMDs) and their heterostructures have been widely studied for next-generation electronics. However, the following critical challenges have hindered them from their commercialization: 1) precise layer control during their growth, 2) maintaining single crystallinity at wafer-scale, and 3) inevitable transfer-process to fabricate heterostructure for various next-generation applications such as spintronics, valleytronics, and optoelectronics. This thesis introduces a confined-growth technique that can overcome the aforementioned hurdles simultaneously by introducing a geometric SiO₂ mask that has growth selectivity from the underlying substrate. As micrometer-scale SiO₂ trenches reduce the growth duration substantially, single-domain WSe₂ and MoS₂ arrays are obtained on an arbitrary substrate at wafer-scale by filling the trenches before the second layer of nuclei is introduced, thus enabling layer-by-layer growth without requiring epitaxial seeding. In addition, subsequent MoS₂ growth on the WSe₂ arrays yields MoS₂/WSe₂ heterostructures. Therefore, we for the first time demonstrate single-domain TMDs arrays and their heterostructures at wafer-scale with controllable thickness, which of performances are comparable to that fabricated from TMDs flake. This confined-growth technique not only can overcome key obstacles of 2D materials, but also provide a platform with great potential for next-generation 2D-material-based applications."],"dc:description.degree":["S.M."],"dc:identifier.uri":["https://hdl.handle.net/1721.1/151894"],"dc:publisher":["Massachusetts Institute of Technology"],"dc:rights":["In Copyright - Educational Use Permitted","Copyright retained by author(s)"],"dc:rights.uri":["https://rightsstatements.org/page/InC-EDU/1.0/"],"dc:title":["Layer-by-Layer Single-crystal Two-dimensional Material Growth by Geometric Confinement"],"dc:type":["Thesis"],"thesis:degree_name":["Master","Master of Science in Mechanical Engineering"]},"updated_at":"2026-07-22T22:21:53Z"}