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Chen J, Ma Q, Wu XJ, Li L, Liu J, Zhang H. Wet-Chemical Synthesis and Applications of Semiconductor Nanomaterial-Based Epitaxial Heterostructures. NANO-MICRO LETTERS 2019; 11:86. [PMID: 34138028 PMCID: PMC7770813 DOI: 10.1007/s40820-019-0317-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 09/29/2019] [Indexed: 05/19/2023]
Abstract
Semiconductor nanomaterial-based epitaxial heterostructures with precisely controlled compositions and morphologies are of great importance for various applications in optoelectronics, thermoelectrics, and catalysis. Until now, various kinds of epitaxial heterostructures have been constructed. In this minireview, we will first introduce the synthesis of semiconductor nanomaterial-based epitaxial heterostructures by wet-chemical methods. Various architectures based on different kinds of seeds or templates are illustrated, and their growth mechanisms are discussed in detail. Then, the applications of epitaxial heterostructures in optoelectronics, catalysis, and thermoelectrics are described. Finally, we provide some challenges and personal perspectives for the future research directions of semiconductor nanomaterial-based epitaxial heterostructures.
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Affiliation(s)
- Junze Chen
- Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Qinglang Ma
- Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Xue-Jun Wu
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, People's Republic of China
| | - Liuxiao Li
- Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Jiawei Liu
- Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Hua Zhang
- Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong, People's Republic of China.
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Cheng CP, Chen WS, Cheng YT, Wan HW, Yang CY, Pi TW, Kwo J, Hong M. Atomic Nature of the Growth Mechanism of Atomic Layer Deposited High-κ Y 2O 3 on GaAs(001)-4 × 6 Based on in Situ Synchrotron Radiation Photoelectron Spectroscopy. ACS OMEGA 2018; 3:2111-2118. [PMID: 31458518 PMCID: PMC6641429 DOI: 10.1021/acsomega.7b01564] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 02/09/2018] [Indexed: 06/10/2023]
Abstract
Y2O3 was in situ deposited on a freshly grown molecular beam epitaxy GaAs(001)-4 × 6 surface by atomic layer deposition (ALD). In situ synchrotron radiation photoemission was used to study the mechanism of the tris(ethylcyclopentadienyl)yttrium [Y(CpEt)3] and H2O process. The exponential attenuation of Ga 3d photoelectrons confirmed the laminar growth of ALD-Y2O3. In the embryo stage of the first ALD half-cycle with only Y(CpEt)3, the precursors reside on the faulted As atoms and undergo a charge transfer to the bonded As atoms. The subsequent ALD half-cycle of H2O molecules removes the bonded As atoms, and the oxygen atoms bond with the underneath Ga atoms. The product of a line of Ga-O-Y bonds stabilizes the Y2O3 films on the GaAs substrate. The resulting coordinatively unsaturated Y-O pairs of Y2O3 open the next ALD series. The absence of Ga2O3, As2O3, and As2O5 states may play an important role in the attainment of low interfacial trap densities (D it) of <1012 cm-2 eV-1 in our established reports.
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Affiliation(s)
- Chiu-Ping Cheng
- Department
of Electrophysics, National Chiayi University, Chiayi 60004, Taiwan, ROC
| | - Wan-Sin Chen
- Graduate
Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan, ROC
| | - Yi-Ting Cheng
- Graduate
Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan, ROC
| | - Hsien-Wen Wan
- Graduate
Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan, ROC
| | - Cheng-Yeh Yang
- Department
of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC
| | - Tun-Wen Pi
- National
Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan, ROC
| | - Jueinai Kwo
- Department
of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC
| | - Minghwei Hong
- Graduate
Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan, ROC
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Lawrenz F, Lange P, Severin N, Rabe JP, Helm CA, Block S. Morphology, mechanical stability, and protective properties of ultrathin gallium oxide coatings. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:5836-5842. [PMID: 25945521 DOI: 10.1021/acs.langmuir.5b00871] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Ultrathin gallium oxide layers with a thickness of 2.8 ± 0.2 nm were transferred from the surface of liquid gallium onto solid substrates, including conjugated polymer poly(3-hexylthiophene) (P3HT). The gallium oxide exhibits high mechanical stability, withstanding normal pressures of up to 1 GPa in contact mode scanning force microscopy imaging. Moreover, it lowers the rate of photodegradation of P3HT by 4 orders of magnitude, as compared to uncovered P3HT. This allows us to estimate the upper limits for oxygen and water vapor transmission rates of 0.08 cm(3) m(-2) day(-1) and 0.06 mg m(-2) day(-1), respectively. Hence, similar to other highly functional coatings such as graphene, ultrathin gallium oxide layers can be regarded as promising candidates for protective layers in flexible organic (opto-)electronics and photovoltaics because they offer permeation barrier functionalities in conjunction with high optical transparency.
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Affiliation(s)
- Frank Lawrenz
- †Institut für Physik, Ernst-Moritz-Arndt Universität, Felix-Hausdorff-Str. 6, D-17487 Greifswald, Germany
| | | | | | | | - Christiane A Helm
- †Institut für Physik, Ernst-Moritz-Arndt Universität, Felix-Hausdorff-Str. 6, D-17487 Greifswald, Germany
| | - Stephan Block
- †Institut für Physik, Ernst-Moritz-Arndt Universität, Felix-Hausdorff-Str. 6, D-17487 Greifswald, Germany
- §Applied Physics, Chalmers University of Technology, Fysikgränd 3, SE-412 96 Gothenburg, Sweden
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Kent T, Chagarov E, Edmonds M, Droopad R, Kummel AC. Dual passivation of intrinsic defects at the compound semiconductor/oxide interface using an oxidant and a reductant. ACS NANO 2015; 9:4843-4849. [PMID: 25844578 DOI: 10.1021/nn5063003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Studies have shown that metal oxide semiconductor field-effect transistors fabricated utilizing compound semiconductors as the channel are limited in their electrical performance. This is attributed to imperfections at the semiconductor/oxide interface which cause electronic trap states, resulting in inefficient modulation of the Fermi level. The physical origin of these states is still debated mainly because of the difficulty in assigning a particular electronic state to a specific physical defect. To gain insight into the exact source of the electronic trap states, density functional theory was employed to model the intrinsic physical defects on the InGaAs (2 × 4) surface and to model the effective passivation of these defects by utilizing both an oxidant and a reductant to eliminate metallic bonds and dangling-bond-induced strain at the interface. Scanning tunneling microscopy and spectroscopy were employed to experimentally determine the physical and electronic defects and to verify the effectiveness of dual passivation with an oxidant and a reductant. While subsurface chemisorption of oxidants on compound semiconductor substrates can be detrimental, it has been shown theoretically and experimentally that oxidants are critical to removing metallic defects at oxide/compound semiconductor interfaces present in nanoscale channels, oxides, and other nanostructures.
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Affiliation(s)
| | | | | | - Ravi Droopad
- §Department of Physics, Texas State University San Marcos, Texas 78666, United States
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Tuominen M, Yasir M, Lång J, Dahl J, Kuzmin M, Mäkelä J, Punkkinen M, Laukkanen P, Kokko K, Schulte K, Punkkinen R, Korpijärvi VM, Polojärvi V, Guina M. Oxidation of the GaAs semiconductor at the Al2O3/GaAs junction. Phys Chem Chem Phys 2015; 17:7060-6. [PMID: 25686555 DOI: 10.1039/c4cp05972g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Atomic-scale understanding and processing of the oxidation of III-V compound-semiconductor surfaces are essential for developing materials for various devices (e.g., transistors, solar cells, and light emitting diodes). The oxidation-induced defect-rich phases at the interfaces of oxide/III-V junctions significantly affect the electrical performance of devices. In this study, a method to control the GaAs oxidation and interfacial defect density at the prototypical Al2O3/GaAs junction grown via atomic layer deposition (ALD) is demonstrated. Namely, pre-oxidation of GaAs(100) with an In-induced c(8 × 2) surface reconstruction, leading to a crystalline c(4 × 2)-O interface oxide before ALD of Al2O3, decreases band-gap defect density at the Al2O3/GaAs interface. Concomitantly, X-ray photoelectron spectroscopy (XPS) from these Al2O3/GaAs interfaces shows that the high oxidation state of Ga (Ga2O3 type) decreases, and the corresponding In2O3 type phase forms when employing the c(4 × 2)-O interface layer. Detailed synchrotron-radiation XPS of the counterpart c(4 × 2)-O oxide of InAs(100) has been utilized to elucidate the atomic structure of the useful c(4 × 2)-O interface layer and its oxidation process. The spectral analysis reveals that three different oxygen sites, five oxidation-induced group-III atomic sites with core-level shifts between -0.2 eV and +1.0 eV, and hardly any oxygen-induced changes at the As sites form during the oxidation. These results, discussed within the current atomic model of the c(4 × 2)-O interface, provide insight into the atomic structures of oxide/III-V interfaces and a way to control the semiconductor oxidation.
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Affiliation(s)
- Marjukka Tuominen
- Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland.
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Colleoni D, Miceli G, Pasquarello A. Origin of Fermi-level pinning at GaAs surfaces and interfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:492202. [PMID: 25372411 DOI: 10.1088/0953-8984/26/49/492202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Through first-principles simulation methods, we assign the origin of Fermi-level pinning at GaAs surfaces and interfaces to the bistability between the As-As dimer and two As dangling bonds, which transform into each other upon charge trapping. This defect is shown to be naturally formed both at GaAs surfaces upon oxygen deposition and in the near-interface substoichiometric oxide. Using electron-counting arguments, we infer that the identified defect occurs in opposite charge states. The Fermi-level pinning then results from the amphoteric nature of this defect which drives the Fermi level to its defect level. These results account for the experimental characterization at both GaAs surfaces and interfaces within a unified picture, wherein the role of As antisites is elucidated.
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Affiliation(s)
- Davide Colleoni
- Chaire de Simulation à l'Echelle Atomique (CSEA), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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Chagarov EA, Kummel AC. Density functional theory simulations of amorphous high-κ oxides on a compound semiconductor alloy: a-Al2O3/InGaAs(100)-(4×2), a-HfO2/InGaAs(100)-(4×2), and a-ZrO2/InGaAs(100)-(4×2). J Chem Phys 2011; 135:244705. [DOI: 10.1063/1.3657439] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Bishop SR, Clemens JB, Chagarov EA, Shen J, Kummel AC. Theoretical analysis of initial adsorption of high-κ metal oxides on InxGa1−xAs(0 0 1)-(4×2) surfaces. J Chem Phys 2010; 133:194702. [DOI: 10.1063/1.3501371] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Shen J, Chagarov EA, Feldwinn DL, Melitz W, Santagata NM, Kummel AC, Droopad R, Passlack M. Scanning tunneling microscopy/spectroscopy study of atomic and electronic structures of In2O on InAs and In0.53Ga0.47As(001)-(4×2) surfaces. J Chem Phys 2010; 133:164704. [PMID: 21033816 DOI: 10.1063/1.3497040] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Interfacial bonding geometry and electronic structures of In(2)O on InAs and In(0.53)Ga(0.47)As(001)-(4×2) have been investigated by scanning tunneling microscopy/scanning tunneling spectroscopy (STM/STS). STM images show that the In(2)O forms an ordered monolayer on both InAs and InGaAs surfaces. In(2)O deposition on the InAs(001)-(4×2) surface does not displace any surface atoms during both room temperature deposition and postdeposition annealing. Oxygen atoms from In(2)O molecules bond with trough In/Ga atoms on the surface to form a new layer of O-In/Ga bonds, which restore many of the strained trough In/Ga atoms into more bulklike tetrahedral sp(3) bonding environments. STS reveals that for both p-type and n-type clean In(0.53)Ga(0.47)As(001)-(4×2) surfaces, the Fermi level resides near the valence band maximum (VBM); however, after In(2)O deposition and postdeposition annealings, the Fermi level position is close to the VBM for p-type samples and close to the conduction band minimum for n-type samples. This result indicates that In(2)O bonding eliminates surface states within the bandgap and forms an unpinned interface when bonding with In(0.53)Ga(0.47)As/InP(001)-(4×2). Density function theory is used to confirm the experimental finding.
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Affiliation(s)
- Jian Shen
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093, USA.
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Clemens JB, Bishop SR, Lee JS, Kummel AC, Droopad R. Initiation of a passivated interface between hafnium oxide and In(Ga)As(0 0 1)−(4×2). J Chem Phys 2010; 132:244701. [DOI: 10.1063/1.3427584] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Winn DL, Hale MJ, Grassman TJ, Sexton JZ, Kummel AC, Passlack M, Droopad R. Electronic properties of adsorbates on GaAs(001)-c(2x8)/(2x4). J Chem Phys 2007; 127:134705. [PMID: 17919041 DOI: 10.1063/1.2786097] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A systematic experimental and theoretical study was performed to determine the causes of oxide-induced Fermi level pinning and unpinning on GaAs(001)-c(2 x 8)/(2 x 4). Scanning tunneling spectroscopy (STS) and density functional theory (DFT) were used to study four different adsorbates' (O(2), In(2)O, Ga(2)O, and SiO) bonding to the GaAs(001)-c(2 x 8)/(2 x 4) surface. The STS results revealed that out of the four adsorbates studied, only one left the Fermi level unpinned, Ga(2)O. DFT calculations were used to elucidate the causes of the Fermi level pinning. Two distinct pinning mechanisms were identified: direct (adsorbate induced states in the band gap region) and indirect pinnings (generation of undimerized As atoms). For O(2) dissociative chemisorption onto GaAs(001)-c(2 x 8)/(2 x 4), the Fermi level pinning was only indirect, while direct Fermi level pinning was observed when In(2)O was deposited on GaAs(001)-c(2 x 8)/(2 x 4). In the case of SiO on GaAs(001)-c(2 x 8)/(2 x 4), the Fermi level pinning was a combination of the two mechanisms.
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Affiliation(s)
- Darby L Winn
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA
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Hale MJ, Yi SI, Sexton JZ, Kummel AC, Passlack M. Erratum: “Scanning tunneling microscopy and spectroscopy of gallium oxide deposition and oxidation on GaAs(001)-c(2×8)∕(2×4)” [J. Chem. Phys. 119, 6719 (2003)]. J Chem Phys 2007. [DOI: 10.1063/1.2748759] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Winn DL, Hale MJ, Grassman TJ, Kummel AC, Droopad R, Passlack M. Direct and indirect causes of Fermi level pinning at the SiO∕GaAs interface. J Chem Phys 2007; 126:084703. [PMID: 17343465 DOI: 10.1063/1.2363183] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The correlation between atomic bonding sites and the electronic structure of SiO on GaAs(001)-c(2x8)/(2x4) was investigated using scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), and density functional theory (DFT). At low coverage, STM images reveal that SiO molecules bond Si end down; this is consistent with Si being undercoordinated and O being fully coordinated in molecular SiO. At approximately 5% ML (monolayer) coverage, multiple bonding geometries were observed. To confirm the site assignments from STM images, DFT calculations were used to estimate the total adsorption energies of the different bonding geometries as a function of SiO coverage. STS measurements indicated that SiO pins the Fermi level midgap at approximately 5% ML coverage. DFT calculations reveal that the direct causes of Fermi level pinning at the SiO GaAs(001)-(2x4) interface are a result of either local charge buildups or the generation of partially filled dangling bonds on Si atoms.
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Affiliation(s)
- Darby L Winn
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA
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Hale MJ, Winn DL, Grassman TJ, Kummel AC, Droopad R. Chemically resolved scanning tunneling microscopy imaging of Al on p-type Al0.1Ga0.9As(001)‐c(2×8)∕(2×4). J Chem Phys 2005; 122:124702. [PMID: 15836404 DOI: 10.1063/1.1846051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The ability to chemically differentiate individual subsurface Al and Ga atoms, when imaging the Al0.1Ga0.9As(001)-c(2x8)(2x4) surface with scanning tunneling microscopy (STM), has been observed for the first time. In filled-state STM images first layer As atoms bonded to second layer Al atoms appear brighter than those bonded to second layer Ga atoms. This effect is only observed experimentally with p-type Al0.1Ga0.9As grown on p-type GaAs substrates and has been computationally modeled with density functional theory (DFT) calculations. It is hypothesized that chemical specificity is not observed on n-type material because the extra surface charge given to first layer As atoms by second layer Al atoms adds negligibly to the filled-state density of the surface, thus preventing the visualization of chemical specificity with filled-state STM imaging. The ability to distinguish whether first layer As atoms are bonded to second layer Ga and/or Al atoms in STM images shows that small differences in bond ionicity affect the local electronic structure of the material.
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Affiliation(s)
- M J Hale
- Department of Chemistry, 0358, University of California, San Diego, La Jolla, California 92093, USA
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Development methodology for high-κ gate dielectrics on III–V semiconductors: Gd[sub x]Ga[sub 0.4−x]O[sub 0.6]∕Ga[sub 2]O[sub 3] dielectric stacks on GaAs. ACTA ACUST UNITED AC 2005. [DOI: 10.1116/1.1943448] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Hale MJ, Sexton JZ, Winn DL, Kummel AC, Erbudak M, Passlack M. The influence of bond flexibility and molecular size on the chemically selective bonding of In2O and Ga2O on GaAs(001)-c(2×8)/(2×4). J Chem Phys 2004; 120:5745-54. [PMID: 15267453 DOI: 10.1063/1.1648016] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The surface structures formed upon deposition of In2O and Ga2O by molecular beam epitaxy onto the arsenic-rich GaAs(001)-c(2 x 8)/(2 x 4) surface have been studied using scanning tunneling microscopy and density functional theory. In2O initially bonds, with indium atoms bonding to second layer gallium atoms within the trough, and proceeds to insert into or between first layer arsenic dimer pairs. In contrast, Ga2O only inserts into or between arsenic dimer pairs due to chemical site constraints. The calculated energy needed to bend a Ga2O molecule approximately 70 degrees, so that it can fit into an arsenic dimer pair, is 0.6 eV less than that required for In2O. The greater flexibility of the Ga2O molecule causes its insertion site to be 0.77 eV more exothermic than the In2O insertion site. This result shows that although trends in the periodic table can be used to predict some surface reactions, small changes in atomic size can play a significant role in the chemistry of gas/surface reactions through the indirect effects of bond angle flexibility and bond length stiffness.
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Affiliation(s)
- M J Hale
- Department of Chemistry, 0358, University of California, San Diego, La Jolla, California 92093, USA
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