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  • 1
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Fully-coherent Si0.7Ge0.3 layers were deposited on Si(001) by gas-source molecular beam epitaxy (GS-MBE) from Ge2H6/Si2H6 mixtures in order to probe the effect of steady-state hydrogen coverages θH on surface morphological evolution during the growth of compressively strained films. The layers are grown as a function of thickness t at temperatures, Ts=450–550 °C, for which strain-induced roughening is observed during solid-source MBE (SS-MBE) and deposition from hyperthermal beams. With GS-MBE, we obtain three-dimensional (3D) strain-induced growth mounds in samples deposited at Ts=550 °C for which θH is small, 0.11 monolayer (ML). However, mound formation is dramatically suppressed at 500 °C (θH=0.26 ML) and completely eliminated at 450 °C (θH=0.52 ML). We attribute these large differences in surface morphological evolution primarily to θH(Ts)-induced effects on film growth rates R, adatom diffusion rates Ds, and ascending step-crossing probabilities. GS-MBE Si0.7Ge0.3(001) growth at 450 °C remains two dimensional, with a surface width 〈w〉〈0.15 nm, at all film thicknesses t=11–80 nm, since both R and the rate of mass transport across ascending steps are low. Raising Ts to 500 °C increases R faster than Ds leading to shorter mean surface diffusion lengths and the formation of extremely shallow, rounded growth mounds for which 〈w〉 remains essentially constant at (similar, equals)0.2 nm while the in-plane coherence length 〈d〉 increases from (similar, equals)70 nm at t=14 nm to 162 nm with t=75 nm. The low ascending step crossing probability at 500 °C results in mounds that spread laterally, rather than vertically, due to preferential attachment at the mound edges. At Ts=550 °C, the ascending step crossing probability increases due to both higher thermal activation and lower hydrogen coverages. 〈w〉(t) increases by more than a factor of 10, from 0.13 nm at t=15 nm to 1.9 nm at t=105 nm, while the in-plane coherence length 〈d〉 remains constant at (similar, equals)85 nm. This leads, under the strain driving force, to the formation of self-organized 3D {105}-faceted pyramids at 550 °C which are very similar to those observed during SS-MBE. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 3808-3810 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the growth of epitaxial metastable B1 NaCl structure TaN(001) layers. The films were grown on MgO(001) at 600 °C by ultrahigh vacuum reactive magnetron sputter deposition in mixed Ar/N2 discharges maintained at 20 mTorr (2.67 Pa). X-ray diffraction and transmission electron microscopy results establish the epitaxial relationship as cube-on-cube, (001)TaN(parallel)(001)MgO with [100]TaN(parallel)[100]MgO, while Rutherford backscattering spectroscopy shows that the layers are overstoichiometric with N/Ta=1.22±0.02. The room-temperature resistivity is 225 μΩ cm with a small negative temperature dependence between 20 and 400 K. The hardness and elastic modulus, as determined by nanoindentation measurements, are 30.8±0.9 and 457±16 GPa, respectively. © 1999 American Institute of Physics.
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  • 3
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Mn–O and Mn–Mn interatomic distances were determined in LaxCa1−xMnO3 films grown heteroepitaxially on single crystal SrTiO3 and LaAlO3 substrates by molecular beam epitaxy. Mn–O bond lengths were found to be fixed at ∼1.975 Å for both types of substrates, while the Mn–Mn distance was detected to be larger for films grown on SrTiO3 substrates than for films grown on LaAlO3. The deviation of Mn–Mn interatomic distances, and subsequently Mn–O–Mn bond angles, in epitaxial LaxCa1−xMnO3 films is attributed to the misfit strain: compressive for LaAlO3 and tensile for SrTiO3 substrates. © 2001 American Institute of Physics.
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  • 4
    ISSN: 0921-4534
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 5
    Publication Date: 2015-08-15
    Description: Oxide heterostructures often exhibit unusual physical properties that are absent in the constituent bulk materials. Here, we report an atomically sharp transition to a ferromagnetic phase when polar antiferromagnetic LaMnO3 (001) films are grown on SrTiO3 substrates. For a thickness of six unit cells or more, the LaMnO3 film abruptly becomes ferromagnetic over its entire area, which is visualized by scanning superconducting quantum interference device microscopy. The transition is explained in terms of electronic reconstruction originating from the polar nature of the LaMnO3 (001) films. Our results demonstrate that functionalities can be engineered in oxide films that are only a few atomic layers thick.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wang, X Renshaw -- Li, C J -- Lu, W M -- Paudel, T R -- Leusink, D P -- Hoek, M -- Poccia, N -- Vailionis, A -- Venkatesan, T -- Coey, J M D -- Tsymbal, E Y -- Ariando -- Hilgenkamp, H -- New York, N.Y. -- Science. 2015 Aug 14;349(6249):716-9. doi: 10.1126/science.aaa5198.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉MESA+ Institute for Nanotechnology, University of Twente, Enschede, Netherlands. wang.xiao@utwente.nl venky@nus.edu.sg. ; NUSNNI-Nanocore, National University of Singapore, Singapore. NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore. ; NUSNNI-Nanocore, National University of Singapore, Singapore. ; Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE, USA. ; MESA+ Institute for Nanotechnology, University of Twente, Enschede, Netherlands. ; Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, USA. ; NUSNNI-Nanocore, National University of Singapore, Singapore. NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore. Department of Physics, National University of Singapore, Singapore. Department of Electrical and Computer Engineering and Department of Materials Science and Engineering, National University of Singapore, Singapore. wang.xiao@utwente.nl venky@nus.edu.sg. ; NUSNNI-Nanocore, National University of Singapore, Singapore. School of Physics and Centre for Research on Adaptive Nanostructures and Nanodevices, Trinity College, Dublin, Ireland. ; NUSNNI-Nanocore, National University of Singapore, Singapore. Department of Physics, National University of Singapore, Singapore.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26273050" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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