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Zhou T, Dartiailh MC, Sardashti K, Han JE, Matos-Abiague A, Shabani J, Žutić I. Fusion of Majorana bound states with mini-gate control in two-dimensional systems. Nat Commun 2022; 13:1738. [PMID: 35365644 PMCID: PMC8976011 DOI: 10.1038/s41467-022-29463-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 03/16/2022] [Indexed: 11/09/2022] Open
Abstract
A hallmark of topological superconductivity is the non-Abelian statistics of Majorana bound states (MBS), its chargeless zero-energy emergent quasiparticles. The resulting fractionalization of a single electron, stored nonlocally as a two spatially-separated MBS, provides a powerful platform for implementing fault-tolerant topological quantum computing. However, despite intensive efforts, experimental support for MBS remains indirect and does not probe their non-Abelian statistics. Here we propose how to overcome this obstacle in mini-gate controlled planar Josephson junctions (JJs) and demonstrate non-Abelian statistics through MBS fusion, detected by charge sensing using a quantum point contact, based on dynamical simulations. The feasibility of preparing, manipulating, and fusing MBS in two-dimensional (2D) systems is supported in our experiments which demonstrate the gate control of topological transition and superconducting properties with five mini gates in InAs/Al-based JJs. While we focus on this well-established platform, where the topological superconductivity was already experimentally detected, our proposal to identify elusive non-Abelian statistics motivates also further MBS studies in other gate-controlled 2D systems.
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Affiliation(s)
- Tong Zhou
- Department of Physics, University at Buffalo, State University of New York, Buffalo, NY, 14260, USA.
| | - Matthieu C Dartiailh
- Center for Quantum Phenomena, Department of Physics, New York University, New York, NY, 10003, USA
| | - Kasra Sardashti
- Center for Quantum Phenomena, Department of Physics, New York University, New York, NY, 10003, USA
| | - Jong E Han
- Department of Physics, University at Buffalo, State University of New York, Buffalo, NY, 14260, USA
| | - Alex Matos-Abiague
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, 48201, USA
| | - Javad Shabani
- Center for Quantum Phenomena, Department of Physics, New York University, New York, NY, 10003, USA
| | - Igor Žutić
- Department of Physics, University at Buffalo, State University of New York, Buffalo, NY, 14260, USA.
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2
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Elfeky BH, Lotfizadeh N, Schiela WF, Strickland WM, Dartiailh M, Sardashti K, Hatefipour M, Yu P, Pankratova N, Lee H, Manucharyan VE, Shabani J. Local Control of Supercurrent Density in Epitaxial Planar Josephson Junctions. Nano Lett 2021; 21:8274-8280. [PMID: 34570504 DOI: 10.1021/acs.nanolett.1c02771] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The critical current response to an applied out-of-plane magnetic field in a Josephson junction provides insight into the uniformity of its current distribution. In Josephson junctions with semiconducting weak links, the carrier density, and therefore the overall current distribution, can be modified electrostatically via metallic gates. Here, we show local control of the current distribution in an epitaxial Al-InAs Josephson junction equipped with five minigates. We demonstrate that not only can the junction width be electrostatically defined but also the current profile can be locally adjusted to form superconducting quantum interference devices. Our studies show enhanced edge conduction in such long junctions, which can be eliminated by minigates to create a uniform current distribution.
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Affiliation(s)
- Bassel Heiba Elfeky
- Department of Physics, New York University, New York, New York 10003, United States
| | - Neda Lotfizadeh
- Department of Physics, New York University, New York, New York 10003, United States
| | - William F Schiela
- Department of Physics, New York University, New York, New York 10003, United States
| | - William M Strickland
- Department of Physics, New York University, New York, New York 10003, United States
| | - Matthieu Dartiailh
- Department of Physics, New York University, New York, New York 10003, United States
| | - Kasra Sardashti
- Department of Physics, New York University, New York, New York 10003, United States
| | - Mehdi Hatefipour
- Department of Physics, New York University, New York, New York 10003, United States
| | - Peng Yu
- Department of Physics, New York University, New York, New York 10003, United States
| | - Natalia Pankratova
- Department of Physics, Joint Quantum Institute, and Quantum Materials Center, University of Maryland, College Park, Maryland 20742, United States
| | - Hanho Lee
- Department of Physics, Joint Quantum Institute, and Quantum Materials Center, University of Maryland, College Park, Maryland 20742, United States
| | - Vladimir E Manucharyan
- Department of Physics, Joint Quantum Institute, and Quantum Materials Center, University of Maryland, College Park, Maryland 20742, United States
| | - Javad Shabani
- Department of Physics, New York University, New York, New York 10003, United States
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3
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Barati F, Thompson JP, Dartiailh MC, Sardashti K, Mayer W, Yuan J, Wickramasinghe K, Watanabe K, Taniguchi T, Churchill H, Shabani J. Tuning Supercurrent in Josephson Field-Effect Transistors Using h-BN Dielectric. Nano Lett 2021; 21:1915-1920. [PMID: 33617256 DOI: 10.1021/acs.nanolett.0c03183] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Epitaxial Al-InAs heterostructures appear as a promising materials platform for exploring mesoscopic and topological superconductivity. A unique property of Josephson junction field effect transistors (JJ-FETs) fabricated on these heterostructures is the ability to tune the supercurrent using a metallic gate. Here, we report the fabrication and measurement of gate-tunable Al-InAs JJ-FETs in which the gate dielectric in contact with the InAs is produced by mechanically exfoliated hexagonal boron nitride (h-BN) followed by dry transfer. We discuss a versatile fabrication process that enables compatibility between layered material transfer and Al-InAs heterostructures that allows us to achieve full gate-tunability of supercurrent by using only 5 nm thick h-BN flakes. Our study shows that pristine properties of epitaxial Josephson junctions, such as product of normal resistance and critical current, IcRn, are preserved. Furthermore, complementary measurements confirm that using h-BN dielectric changes the channel density less when compared to atomic layer deposition of Al2O3.
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Affiliation(s)
- Fatemeh Barati
- Center for Quantum Phenomena, Department of Physics, New York University, New York City, New York 10003, United States
| | - Josh P Thompson
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Matthieu C Dartiailh
- Center for Quantum Phenomena, Department of Physics, New York University, New York City, New York 10003, United States
| | - Kasra Sardashti
- Center for Quantum Phenomena, Department of Physics, New York University, New York City, New York 10003, United States
| | - William Mayer
- Center for Quantum Phenomena, Department of Physics, New York University, New York City, New York 10003, United States
| | - Joseph Yuan
- Center for Quantum Phenomena, Department of Physics, New York University, New York City, New York 10003, United States
| | - Kaushini Wickramasinghe
- Center for Quantum Phenomena, Department of Physics, New York University, New York City, New York 10003, United States
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Hugh Churchill
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Javad Shabani
- Center for Quantum Phenomena, Department of Physics, New York University, New York City, New York 10003, United States
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4
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Sardashti K, Chagarov E, Antunez PD, Gershon TS, Ueda ST, Gokmen T, Bishop D, Haight R, Kummel AC. Nanoscale Characterization of Back Surfaces and Interfaces in Thin-Film Kesterite Solar Cells. ACS Appl Mater Interfaces 2017; 9:17024-17033. [PMID: 28452464 DOI: 10.1021/acsami.7b01838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Combinations of sub 1 μm absorber films with high-work-function back surface contact layers are expected to induce large enough internal fields to overcome adverse effects of bulk defects on thin-film photovoltaic performance, particularly in earth-abundant kesterites. However, there are numerous experimental challenges involving back surface engineering, which includes exfoliation, thinning, and contact layer optimization. In the present study, a unique combination of nanocharacterization tools, including nano-Auger, Kelvin probe force microscopy (KPFM), and cryogenic focused ion beam measurements, are employed to gauge the possibility of surface potential modification in the absorber back surface via direct deposition of high-work-function metal oxides on exfoliated surfaces. Nano-Auger measurements showed large compositional nonuniformities on the exfoliated surfaces, which can be minimized by a brief bromine-methanol etching step. Cross-sectional nano-Auger and KPFM measurements on Au/MoO3/Cu2ZnSn(S,Se)4 (CZTSSe) showed an upward band bending as large as 400 meV within the CZTSSe layer, consistent with the high work function of MoO3, despite Au incorporation into the oxide layer. Density functional theory simulations of the atomic structure for bulk amorphous MoO3 demonstrated the presence of large voids within MoO3 enabling Au in-diffusion. With a less diffusive metal electrode such as Pt or Pd, upward band bending beyond this level is expected to be achieved.
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Affiliation(s)
| | | | - Priscilla D Antunez
- IBM T. J. Watson Research Center , 1101 Kitchawan Road, Yorktown Heights, New York 10598, United States
| | - Talia S Gershon
- IBM T. J. Watson Research Center , 1101 Kitchawan Road, Yorktown Heights, New York 10598, United States
| | | | - Tayfun Gokmen
- IBM T. J. Watson Research Center , 1101 Kitchawan Road, Yorktown Heights, New York 10598, United States
| | - Douglas Bishop
- IBM T. J. Watson Research Center , 1101 Kitchawan Road, Yorktown Heights, New York 10598, United States
| | - Richard Haight
- IBM T. J. Watson Research Center , 1101 Kitchawan Road, Yorktown Heights, New York 10598, United States
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5
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Edmonds M, Sardashti K, Wolf S, Chagarov E, Clemons M, Kent T, Park JH, Tang K, McIntyre PC, Yoshida N, Dong L, Holmes R, Alvarez D, Kummel AC. Low temperature thermal ALD of a SiN x interfacial diffusion barrier and interface passivation layer on Si xGe 1- x(001) and Si xGe 1- x(110). J Chem Phys 2017; 146:052820. [PMID: 28178835 DOI: 10.1063/1.4975081] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Atomic layer deposition of a silicon rich SiNx layer on Si0.7Ge0.3(001), Si0.5Ge0.5(001), and Si0.5Ge0.5(110) surfaces has been achieved by sequential pulsing of Si2Cl6 and N2H4 precursors at a substrate temperature of 285 °C. XPS spectra show a higher binding energy shoulder peak on Si 2p indicative of SiOxNyClz bonding while Ge 2p and Ge 3d peaks show only a small amount of higher binding energy components consistent with only interfacial bonds, indicating the growth of SiOxNy on the SiGe surface with negligible subsurface reactions. Scanning tunneling spectroscopy measurements confirm that the SiNx interfacial layer forms an electrically passive surface on p-type Si0.70Ge0.30(001), Si0.50Ge0.50(110), and Si0.50Ge0.50(001) substrates as the surface Fermi level is unpinned and the electronic structure is free of states in the band gap. DFT calculations show that a Si rich a-SiO0.4N0,4 interlayer can produce lower interfacial defect density than stoichiometric a-SiO0.8N0.8, substoichiometric a-Si3N2, or stoichiometric a-Si3N4 interlayers by minimizing strain and bond breaking in the SiGe by the interlayer. Metal-oxide-semiconductor capacitors devices were fabricated on p-type Si0.7Ge0.3(001) and Si0.5Ge0.5(001) substrates with and without the insertion of an ALD SiOxNy interfacial layer, and the SiOxNy layer resulted in a decrease in interface state density near midgap with a comparable Cmax value.
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Affiliation(s)
- Mary Edmonds
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093, USA
| | - Kasra Sardashti
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093, USA
| | - Steven Wolf
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093, USA
| | - Evgueni Chagarov
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA
| | - Max Clemons
- Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093, USA
| | - Tyler Kent
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093, USA
| | - Jun Hong Park
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093, USA
| | - Kechao Tang
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
| | - Paul C McIntyre
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
| | | | - Lin Dong
- Applied Materials, Sunnyvale, California 94085, USA
| | | | | | - Andrew C Kummel
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093, USA
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6
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Chagarov E, Sardashti K, Haight R, Mitzi DB, Kummel AC. Density-functional theory computer simulations of CZTS0.25Se0.75 alloy phase diagrams. J Chem Phys 2016. [DOI: 10.1063/1.4959591] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- E. Chagarov
- Departments of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA
| | - K. Sardashti
- Departments of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA
| | - R. Haight
- IBM T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, New York 10598, USA
| | - D. B. Mitzi
- Departments of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA
| | - A. C. Kummel
- Departments of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA
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7
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Park JH, Fathipour S, Kwak I, Sardashti K, Ahles CF, Wolf SF, Edmonds M, Vishwanath S, Xing HG, Fullerton-Shirey SK, Seabaugh A, Kummel AC. Atomic Layer Deposition of Al2O3 on WSe2 Functionalized by Titanyl Phthalocyanine. ACS Nano 2016; 10:6888-6896. [PMID: 27305595 DOI: 10.1021/acsnano.6b02648] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
To deposit an ultrathin dielectric onto WSe2, monolayer titanyl phthalocyanine (TiOPc) is deposited by molecular beam epitaxy as a seed layer for atomic layer deposition (ALD) of Al2O3 on WSe2. TiOPc molecules are arranged in a flat monolayer with 4-fold symmetry as measured by scanning tunneling microscopy. ALD pulses of trimethyl aluminum and H2O nucleate on the TiOPc, resulting in a uniform deposition of Al2O3, as confirmed by atomic force microscopy and cross-sectional transmission electron microscopy. The field-effect transistors (FETs) formed using this process have a leakage current of 0.046 pA/μm(2) at 1 V gate bias with 3.0 nm equivalent oxide thickness, which is a lower leakage current than prior reports. The n-branch of the FET yielded a subthreshold swing of 80 mV/decade.
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Affiliation(s)
| | - Sara Fathipour
- Department of Electrical Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | | | | | | | | | | | - Suresh Vishwanath
- Department of Electrical Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Huili Grace Xing
- Department of Electrical Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Susan K Fullerton-Shirey
- Department of Chemical and Petroleum Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15213, United States
| | - Alan Seabaugh
- Department of Electrical Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States
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8
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Sardashti K, Haight R, Anderson R, Contreras M, Fruhberger B, Kummel AC. Grazing Incidence Cross-Sectioning of Thin-Film Solar Cells via Cryogenic Focused Ion Beam: A Case Study on CIGSe. ACS Appl Mater Interfaces 2016; 8:14994-14999. [PMID: 27248803 DOI: 10.1021/acsami.6b04214] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Cryogenic focused ion beam (Cryo-FIB) milling at near-grazing angles is employed to fabricate cross-sections on thin Cu(In,Ga)Se2 with >8x expansion in thickness. Kelvin probe force microscopy (KPFM) on sloped cross sections showed reduction in grain boundaries potential deeper into the film. Cryo Fib-KPFM enabled the first determination of the electronic structure of the Mo/CIGSe back contact, where a sub 100 nm thick MoSey assists hole extraction due to 45 meV higher work function. This demonstrates that CryoFIB-KPFM combination can reveal new targets of opportunity for improvement in thin-films photovoltaics such as high-work-function contacts to facilitate hole extraction through the back interface of CIGS.
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Affiliation(s)
- Kasra Sardashti
- Department of Chemistry and Biochemistry, University of California San Diego , La Jolla, California 92093-0358, United States
| | - Richard Haight
- IBM TJ Watson Research Center , Yorktown Heights, New York 10598, United States
| | - Ryan Anderson
- California Institute for Telecommunications and Information Technology, University of California San Diego , La Jolla, California 92093-0436, United States
| | - Miguel Contreras
- National Renewable Energy Laboratory , Golden, Colorado 80401, United States
| | - Bernd Fruhberger
- California Institute for Telecommunications and Information Technology, University of California San Diego , La Jolla, California 92093-0436, United States
| | - Andrew C Kummel
- Department of Chemistry and Biochemistry, University of California San Diego , La Jolla, California 92093-0358, United States
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9
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Chagarov E, Sardashti K, Kummel AC, Lee YS, Haight R, Gershon TS. Ag2ZnSn(S,Se)4: A highly promising absorber for thin film photovoltaics. J Chem Phys 2016; 144:104704. [DOI: 10.1063/1.4943270] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Evgueni Chagarov
- Department of Chemistry and Biochemistry, University of California, 9500 Gilman Dr, La Jolla, San Diego, California 92093, USA
| | - Kasra Sardashti
- Department of Chemistry and Biochemistry, University of California, 9500 Gilman Dr, La Jolla, San Diego, California 92093, USA
- Materials Science and Engineering Program, University of California, 9500 Gilman Dr, La Jolla, San Diego, California 92093, USA
| | - Andrew C. Kummel
- Department of Chemistry and Biochemistry, University of California, 9500 Gilman Dr, La Jolla, San Diego, California 92093, USA
| | - Yun Seog Lee
- IBM T.J. Watson Research Center, PO Box 218, Yorktown Hts., New York 10598, USA
| | - Richard Haight
- IBM T.J. Watson Research Center, PO Box 218, Yorktown Hts., New York 10598, USA
| | - Talia S. Gershon
- IBM T.J. Watson Research Center, PO Box 218, Yorktown Hts., New York 10598, USA
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10
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Chagarov E, Sardashti K, Kaufman-Osborn T, Madisetti S, Oktyabrsky S, Sahu B, Kummel A. Density-Functional Theory Molecular Dynamics Simulations and Experimental Characterization of a-Al₂O₃/SiGe Interfaces. ACS Appl Mater Interfaces 2015; 7:26275-26283. [PMID: 26575590 DOI: 10.1021/acsami.5b08727] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Density-functional theory molecular dynamics simulations were employed to investigate direct interfaces between a-Al2O3 and Si0.50Ge0.50 with Si- and Ge-terminations. The simulated stacks revealed mixed interfacial bonding. While Si-O and Ge-O bonds are unlikely to be problematic, bonding between Al and Si or Ge could result in metallic bond formation; however, the internal bonds of a-Al2O3 are sufficiently strong to allow just weak Al bonding to the SiGe surface thereby preventing formation of metallic-like states but leave dangling bonds. The oxide/SiGe band gaps were unpinned and close to the SiGe bulk band gap. The interfaces had SiGe dangling bonds, but they were sufficiently filled that they did not produce midgap states. Capacitance-voltage (C-V) spectroscopy and angle-resolved X-ray photoelectron spectroscopy experimentally confirmed formation of interfaces with low interface trap density via direct bonding between a-Al2O3 and SiGe.
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Affiliation(s)
- Evgueni Chagarov
- Department of Chemistry and Biochemistry, University of California, San Diego , La Jolla, California 92093, United States
| | - Kasra Sardashti
- Department of Chemistry and Biochemistry, University of California, San Diego , La Jolla, California 92093, United States
| | | | | | - Serge Oktyabrsky
- Department of Nanoscale Science and Engineering, University at Albany-State University of New York , Albany, New York 12222, United States
| | - Bhagawan Sahu
- GlobalFoundries , Malta, New York 12020, United States
| | - Andrew Kummel
- Department of Chemistry and Biochemistry, University of California, San Diego , La Jolla, California 92093, United States
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11
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Park JH, Movva HCP, Chagarov E, Sardashti K, Chou H, Kwak I, Hu KT, Fullerton-Shirey SK, Choudhury P, Banerjee SK, Kummel AC. In Situ Observation of Initial Stage in Dielectric Growth and Deposition of Ultrahigh Nucleation Density Dielectric on Two-Dimensional Surfaces. Nano Lett 2015; 15:6626-6633. [PMID: 26393281 DOI: 10.1021/acs.nanolett.5b02429] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Several proposed beyond-CMOS devices based on two-dimensional (2D) heterostructures require the deposition of thin dielectrics between 2D layers. However, the direct deposition of dielectrics on 2D materials is challenging due to their inert surface chemistry. To deposit high-quality, thin dielectrics on 2D materials, a flat lying titanyl phthalocyanine (TiOPc) monolayer, deposited via the molecular beam epitaxy, was employed to create a seed layer for atomic layer deposition (ALD) on 2D materials, and the initial stage of growth was probed using in situ STM. ALD pulses of trimethyl aluminum (TMA) and H2O resulted in the uniform deposition of AlOx on the TiOPc/HOPG. The uniformity of the dielectric is consistent with DFT calculations showing multiple reaction sites are available on the TiOPc molecule for reaction with TMA. Capacitors prepared with 50 cycles of AlOx on TiOPc/graphene display a capacitance greater than 1000 nF/cm(2), and dual-gated devices have current densities of 10(-7)A/cm(2) with 40 cycles.
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Affiliation(s)
| | - Hema C P Movva
- Electrical and Computer Engineering, University of Texas at Austin , Austin, Texas 78712, United States
| | | | | | - Harry Chou
- Electrical and Computer Engineering, University of Texas at Austin , Austin, Texas 78712, United States
| | | | | | - Susan K Fullerton-Shirey
- Department of Electrical Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Pabitra Choudhury
- Department of Chemical Engineering, New Mexico Tech , Socorro, New Mexico 87801, United States
| | - Sanjay K Banerjee
- Electrical and Computer Engineering, University of Texas at Austin , Austin, Texas 78712, United States
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12
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Edmonds M, Kent T, Chagarov E, Sardashti K, Droopad R, Chang M, Kachian J, Park JH, Kummel A. Passivation of InGaAs(001)-(2 × 4) by Self-Limiting Chemical Vapor Deposition of a Silicon Hydride Control Layer. J Am Chem Soc 2015; 137:8526-33. [DOI: 10.1021/jacs.5b03660] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | | | | | - Ravi Droopad
- Ingram
School of Engineering, Texas State University, San Marcos, Texas 78666, United States
| | - Mei Chang
- Applied
Materials, 974 East Arques Avenue, Sunnyvale, California 94085, United States
| | - Jessica Kachian
- Applied
Materials, 974 East Arques Avenue, Sunnyvale, California 94085, United States
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13
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Bashouti MY, Sardashti K, Ristein J, Christiansen S. Kinetic study of H-terminated silicon nanowires oxidation in very first stages. Nanoscale Res Lett 2013; 8:41. [PMID: 23336401 PMCID: PMC3599491 DOI: 10.1186/1556-276x-8-41] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 11/27/2012] [Indexed: 05/16/2023]
Abstract
Oxidation of silicon nanowires (Si NWs) is an undesirable phenomenon that has a detrimental effect on their electronic properties. To prevent oxidation of Si NWs, a deeper understanding of the oxidation reaction kinetics is necessary. In the current work, we study the oxidation kinetics of hydrogen-terminated Si NWs (H-Si NWs) as the starting surfaces for molecular functionalization of Si surfaces. H-Si NWs of 85-nm average diameter were annealed at various temperatures from 50°C to 400°C, in short-time spans ranging from 5 to 60 min. At high temperatures (T ≥ 200°C), oxidation was found to be dominated by the oxide growth site formation (made up of silicon suboxides) and subsequent silicon oxide self-limitation. Si-Si backbond oxidation and Si-H surface bond propagation dominated the process at lower temperatures (T < 200°C).
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Affiliation(s)
- Muhammad Y Bashouti
- Max Planck Institute for the Science of Light Physics department Günther-Scharowsky-St. 1, Erlangen, 91058, Germany
| | - Kasra Sardashti
- Max Planck Institute for the Science of Light Physics department Günther-Scharowsky-St. 1, Erlangen, 91058, Germany
| | - Jürgen Ristein
- Technical Physics, University of Erlangen-Nürnberg, Erwin-Rommel St.1, Erlangen, 91058, Germany
| | - Silke Christiansen
- Max Planck Institute for the Science of Light Physics department Günther-Scharowsky-St. 1, Erlangen, 91058, Germany
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Bashouti MY, Sardashti K, Ristein J, Christiansen SH. Early stages of oxide growth in H-terminated silicon nanowires: determination of kinetic behavior and activation energy. Phys Chem Chem Phys 2012; 14:11877-81. [DOI: 10.1039/c2cp41709j] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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