Quasi-two-dimensional electron gas at the interface of γ-Al2O3/SrTiO3 heterostructures grown by atomic layer deposition
We report the formation of a quasi-two-dimensional electron gas (2-DEG) at the interface of γ-Al2O3/TiO2-terminated SrTiO3 (STO) grown by atomic layer deposition (ALD). The ALD growth of Al2O3 on STO(001) single crystal substrates was performed at temperatures in the range of 200–345 °C. Trimethylal...
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creator | Ngo, Thong Q. Goble, Nicholas J. Posadas, Agham Kormondy, Kristy J. Lu, Sirong McDaniel, Martin D. Jordan-Sweet, Jean Smith, David J. Gao, Xuan P. A. Demkov, Alexander A. Ekerdt, John G. |
description | We report the formation of a quasi-two-dimensional electron gas (2-DEG) at the interface of γ-Al2O3/TiO2-terminated SrTiO3 (STO) grown by atomic layer deposition (ALD). The ALD growth of Al2O3 on STO(001) single crystal substrates was performed at temperatures in the range of 200–345 °C. Trimethylaluminum and water were used as co-reactants. In situ reflection high energy electron diffraction, ex situ x-ray diffraction, and ex situ cross-sectional transmission electron microscopy were used to determine the crystallinity of the Al2O3 films. As-deposited Al2O3 films grown above 300 °C were crystalline with the γ-Al2O3 phase. In situ x-ray photoelectron spectroscopy was used to characterize the Al2O3/STO interface, indicating that a Ti3+ feature in the Ti 2p spectrum of STO was formed after 2–3 ALD cycles of Al2O3 at 345 °C and even after the exposure to trimethylaluminum alone at 300 and 345 °C. The interface quasi-2-DEG is metallic and exhibits mobility values of ∼4 and 3000 cm2 V−1 s−1 at room temperature and 15 K, respectively. The interfacial conductivity depended on the thickness of the Al2O3 layer. The Ti3+ signal originated from the near-interfacial region and vanished after annealing in an oxygen environment. |
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A. ; Demkov, Alexander A. ; Ekerdt, John G.</creator><creatorcontrib>Ngo, Thong Q. ; Goble, Nicholas J. ; Posadas, Agham ; Kormondy, Kristy J. ; Lu, Sirong ; McDaniel, Martin D. ; Jordan-Sweet, Jean ; Smith, David J. ; Gao, Xuan P. A. ; Demkov, Alexander A. ; Ekerdt, John G. ; Brookhaven National Lab. (BNL), Upton, NY (United States)</creatorcontrib><description>We report the formation of a quasi-two-dimensional electron gas (2-DEG) at the interface of γ-Al2O3/TiO2-terminated SrTiO3 (STO) grown by atomic layer deposition (ALD). The ALD growth of Al2O3 on STO(001) single crystal substrates was performed at temperatures in the range of 200–345 °C. Trimethylaluminum and water were used as co-reactants. In situ reflection high energy electron diffraction, ex situ x-ray diffraction, and ex situ cross-sectional transmission electron microscopy were used to determine the crystallinity of the Al2O3 films. As-deposited Al2O3 films grown above 300 °C were crystalline with the γ-Al2O3 phase. In situ x-ray photoelectron spectroscopy was used to characterize the Al2O3/STO interface, indicating that a Ti3+ feature in the Ti 2p spectrum of STO was formed after 2–3 ALD cycles of Al2O3 at 345 °C and even after the exposure to trimethylaluminum alone at 300 and 345 °C. The interface quasi-2-DEG is metallic and exhibits mobility values of ∼4 and 3000 cm2 V−1 s−1 at room temperature and 15 K, respectively. The interfacial conductivity depended on the thickness of the Al2O3 layer. The Ti3+ signal originated from the near-interfacial region and vanished after annealing in an oxygen environment.</description><identifier>ISSN: 0021-8979</identifier><identifier>EISSN: 1089-7550</identifier><identifier>DOI: 10.1063/1.4930575</identifier><language>eng</language><publisher>Melville: American Institute of Physics</publisher><subject>Aluminum oxide ; Applied physics ; ATOMIC AND MOLECULAR PHYSICS ; Atomic layer deposition ; Atomic layer epitaxy ; Crystal structure ; Crystallinity ; Electron diffraction ; Electron gas ; Electrons ; Energy transmission ; Heterostructures ; Single crystals ; Strontium titanates ; Substrates ; Thickness ; Thin films ; Titanium ; Titanium dioxide ; Transition metal oxides ; Transitional aluminas ; Transmission electron microscopy ; Two-dimensional electron gas ; X-ray diffraction ; X-ray photoelectron spectroscopy</subject><ispartof>Journal of applied physics, 2015-09, Vol.118 (11)</ispartof><rights>2015 AIP Publishing LLC.</rights><lds50>peer_reviewed</lds50><oa>free_for_read</oa><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-c319t-86d262996eafa5c37520caa1901494d1cf3c98171746506c11c52fc35ee98343</citedby><cites>FETCH-LOGICAL-c319t-86d262996eafa5c37520caa1901494d1cf3c98171746506c11c52fc35ee98343</cites><orcidid>0000-0002-1148-4915 ; 0000000211484915</orcidid></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><link.rule.ids>230,314,776,780,881,27901,27902</link.rule.ids><backlink>$$Uhttps://www.osti.gov/servlets/purl/1354507$$D View this record in Osti.gov$$Hfree_for_read</backlink></links><search><creatorcontrib>Ngo, Thong Q.</creatorcontrib><creatorcontrib>Goble, Nicholas J.</creatorcontrib><creatorcontrib>Posadas, Agham</creatorcontrib><creatorcontrib>Kormondy, Kristy J.</creatorcontrib><creatorcontrib>Lu, Sirong</creatorcontrib><creatorcontrib>McDaniel, Martin D.</creatorcontrib><creatorcontrib>Jordan-Sweet, Jean</creatorcontrib><creatorcontrib>Smith, David J.</creatorcontrib><creatorcontrib>Gao, Xuan P. A.</creatorcontrib><creatorcontrib>Demkov, Alexander A.</creatorcontrib><creatorcontrib>Ekerdt, John G.</creatorcontrib><creatorcontrib>Brookhaven National Lab. (BNL), Upton, NY (United States)</creatorcontrib><title>Quasi-two-dimensional electron gas at the interface of γ-Al2O3/SrTiO3 heterostructures grown by atomic layer deposition</title><title>Journal of applied physics</title><description>We report the formation of a quasi-two-dimensional electron gas (2-DEG) at the interface of γ-Al2O3/TiO2-terminated SrTiO3 (STO) grown by atomic layer deposition (ALD). The ALD growth of Al2O3 on STO(001) single crystal substrates was performed at temperatures in the range of 200–345 °C. Trimethylaluminum and water were used as co-reactants. In situ reflection high energy electron diffraction, ex situ x-ray diffraction, and ex situ cross-sectional transmission electron microscopy were used to determine the crystallinity of the Al2O3 films. As-deposited Al2O3 films grown above 300 °C were crystalline with the γ-Al2O3 phase. In situ x-ray photoelectron spectroscopy was used to characterize the Al2O3/STO interface, indicating that a Ti3+ feature in the Ti 2p spectrum of STO was formed after 2–3 ALD cycles of Al2O3 at 345 °C and even after the exposure to trimethylaluminum alone at 300 and 345 °C. The interface quasi-2-DEG is metallic and exhibits mobility values of ∼4 and 3000 cm2 V−1 s−1 at room temperature and 15 K, respectively. The interfacial conductivity depended on the thickness of the Al2O3 layer. The Ti3+ signal originated from the near-interfacial region and vanished after annealing in an oxygen environment.</description><subject>Aluminum oxide</subject><subject>Applied physics</subject><subject>ATOMIC AND MOLECULAR PHYSICS</subject><subject>Atomic layer deposition</subject><subject>Atomic layer epitaxy</subject><subject>Crystal structure</subject><subject>Crystallinity</subject><subject>Electron diffraction</subject><subject>Electron gas</subject><subject>Electrons</subject><subject>Energy transmission</subject><subject>Heterostructures</subject><subject>Single crystals</subject><subject>Strontium titanates</subject><subject>Substrates</subject><subject>Thickness</subject><subject>Thin films</subject><subject>Titanium</subject><subject>Titanium dioxide</subject><subject>Transition metal oxides</subject><subject>Transitional aluminas</subject><subject>Transmission electron microscopy</subject><subject>Two-dimensional electron gas</subject><subject>X-ray diffraction</subject><subject>X-ray photoelectron spectroscopy</subject><issn>0021-8979</issn><issn>1089-7550</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2015</creationdate><recordtype>article</recordtype><recordid>eNotkEtOwzAQhi0EEuWx4AYWrFik9dhxEi-ripdUqUJ0bxl30rpK42I7gp6Le3AmjMpqFvPN4_8IuQE2BlaJCYxLJZis5QkZAWtUUUvJTsmIMQ5Fo2p1Ti5i3DIG0Ag1Il-vg4muSJ--WLkd9tH53nQUO7Qp-J6uTaQm0bRB6vqEoTUWqW_pz3cx7fhCTN7C0i0E3WBu-pjCYNMQMNJ18J89fT_kab9zlnbmgIGucO-jS_nIFTlrTRfx-r9ekuXjw3L2XMwXTy-z6bywAlQqmmrFK65UhaY10opacmaNAcWgVOUKbCusaqCGuqwkqyyAlby1QiKqRpTiktwe1-bfnI7WJbQb6_s-59MgZClZnaG7I7QP_mPAmPTWDyF7iJoDLyHLq3mm7o-UzUFjwFbvg9uZcNDA9J98DfpfvvgFQq12fw</recordid><startdate>20150921</startdate><enddate>20150921</enddate><creator>Ngo, Thong Q.</creator><creator>Goble, Nicholas J.</creator><creator>Posadas, Agham</creator><creator>Kormondy, Kristy J.</creator><creator>Lu, Sirong</creator><creator>McDaniel, Martin D.</creator><creator>Jordan-Sweet, Jean</creator><creator>Smith, David J.</creator><creator>Gao, Xuan P. A.</creator><creator>Demkov, Alexander A.</creator><creator>Ekerdt, John G.</creator><general>American Institute of Physics</general><general>American Institute of Physics (AIP)</general><scope>AAYXX</scope><scope>CITATION</scope><scope>8FD</scope><scope>H8D</scope><scope>L7M</scope><scope>OIOZB</scope><scope>OTOTI</scope><orcidid>https://orcid.org/0000-0002-1148-4915</orcidid><orcidid>https://orcid.org/0000000211484915</orcidid></search><sort><creationdate>20150921</creationdate><title>Quasi-two-dimensional electron gas at the interface of γ-Al2O3/SrTiO3 heterostructures grown by atomic layer deposition</title><author>Ngo, Thong Q. ; Goble, Nicholas J. ; Posadas, Agham ; Kormondy, Kristy J. ; Lu, Sirong ; McDaniel, Martin D. ; Jordan-Sweet, Jean ; Smith, David J. ; Gao, Xuan P. A. ; Demkov, Alexander A. ; Ekerdt, John G.</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c319t-86d262996eafa5c37520caa1901494d1cf3c98171746506c11c52fc35ee98343</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2015</creationdate><topic>Aluminum oxide</topic><topic>Applied physics</topic><topic>ATOMIC AND MOLECULAR PHYSICS</topic><topic>Atomic layer deposition</topic><topic>Atomic layer epitaxy</topic><topic>Crystal structure</topic><topic>Crystallinity</topic><topic>Electron diffraction</topic><topic>Electron gas</topic><topic>Electrons</topic><topic>Energy transmission</topic><topic>Heterostructures</topic><topic>Single crystals</topic><topic>Strontium titanates</topic><topic>Substrates</topic><topic>Thickness</topic><topic>Thin films</topic><topic>Titanium</topic><topic>Titanium dioxide</topic><topic>Transition metal oxides</topic><topic>Transitional aluminas</topic><topic>Transmission electron microscopy</topic><topic>Two-dimensional electron gas</topic><topic>X-ray diffraction</topic><topic>X-ray photoelectron spectroscopy</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Ngo, Thong Q.</creatorcontrib><creatorcontrib>Goble, Nicholas J.</creatorcontrib><creatorcontrib>Posadas, Agham</creatorcontrib><creatorcontrib>Kormondy, Kristy J.</creatorcontrib><creatorcontrib>Lu, Sirong</creatorcontrib><creatorcontrib>McDaniel, Martin D.</creatorcontrib><creatorcontrib>Jordan-Sweet, Jean</creatorcontrib><creatorcontrib>Smith, David J.</creatorcontrib><creatorcontrib>Gao, Xuan P. A.</creatorcontrib><creatorcontrib>Demkov, Alexander A.</creatorcontrib><creatorcontrib>Ekerdt, John G.</creatorcontrib><creatorcontrib>Brookhaven National Lab. (BNL), Upton, NY (United States)</creatorcontrib><collection>CrossRef</collection><collection>Technology Research Database</collection><collection>Aerospace Database</collection><collection>Advanced Technologies Database with Aerospace</collection><collection>OSTI.GOV - Hybrid</collection><collection>OSTI.GOV</collection><jtitle>Journal of applied physics</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Ngo, Thong Q.</au><au>Goble, Nicholas J.</au><au>Posadas, Agham</au><au>Kormondy, Kristy J.</au><au>Lu, Sirong</au><au>McDaniel, Martin D.</au><au>Jordan-Sweet, Jean</au><au>Smith, David J.</au><au>Gao, Xuan P. A.</au><au>Demkov, Alexander A.</au><au>Ekerdt, John G.</au><aucorp>Brookhaven National Lab. (BNL), Upton, NY (United States)</aucorp><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Quasi-two-dimensional electron gas at the interface of γ-Al2O3/SrTiO3 heterostructures grown by atomic layer deposition</atitle><jtitle>Journal of applied physics</jtitle><date>2015-09-21</date><risdate>2015</risdate><volume>118</volume><issue>11</issue><issn>0021-8979</issn><eissn>1089-7550</eissn><abstract>We report the formation of a quasi-two-dimensional electron gas (2-DEG) at the interface of γ-Al2O3/TiO2-terminated SrTiO3 (STO) grown by atomic layer deposition (ALD). The ALD growth of Al2O3 on STO(001) single crystal substrates was performed at temperatures in the range of 200–345 °C. Trimethylaluminum and water were used as co-reactants. In situ reflection high energy electron diffraction, ex situ x-ray diffraction, and ex situ cross-sectional transmission electron microscopy were used to determine the crystallinity of the Al2O3 films. As-deposited Al2O3 films grown above 300 °C were crystalline with the γ-Al2O3 phase. In situ x-ray photoelectron spectroscopy was used to characterize the Al2O3/STO interface, indicating that a Ti3+ feature in the Ti 2p spectrum of STO was formed after 2–3 ALD cycles of Al2O3 at 345 °C and even after the exposure to trimethylaluminum alone at 300 and 345 °C. The interface quasi-2-DEG is metallic and exhibits mobility values of ∼4 and 3000 cm2 V−1 s−1 at room temperature and 15 K, respectively. The interfacial conductivity depended on the thickness of the Al2O3 layer. The Ti3+ signal originated from the near-interfacial region and vanished after annealing in an oxygen environment.</abstract><cop>Melville</cop><pub>American Institute of Physics</pub><doi>10.1063/1.4930575</doi><orcidid>https://orcid.org/0000-0002-1148-4915</orcidid><orcidid>https://orcid.org/0000000211484915</orcidid><oa>free_for_read</oa></addata></record> |
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subjects | Aluminum oxide Applied physics ATOMIC AND MOLECULAR PHYSICS Atomic layer deposition Atomic layer epitaxy Crystal structure Crystallinity Electron diffraction Electron gas Electrons Energy transmission Heterostructures Single crystals Strontium titanates Substrates Thickness Thin films Titanium Titanium dioxide Transition metal oxides Transitional aluminas Transmission electron microscopy Two-dimensional electron gas X-ray diffraction X-ray photoelectron spectroscopy |
title | Quasi-two-dimensional electron gas at the interface of γ-Al2O3/SrTiO3 heterostructures grown by atomic layer deposition |
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