SiC SURFACE RECONSTRUCTION: RELEVANCY OF ATOMIC STRUCTURE FOR GROWTH TECHNOLOGY

1999 ◽  
Vol 06 (06) ◽  
pp. 1129-1141 ◽  
Author(s):  
U. STARKE ◽  
J. BERNHARDT ◽  
J. SCHARDT ◽  
K. HEINZ
Keyword(s):  
Silicon Oxide ◽  
Electronic Device ◽  
Defect Density ◽  
Ex Situ ◽  
Scanning Tunneling ◽  
Hydrogen Treatment ◽  
Tunneling Microscopy ◽  
Layer Stacking ◽  
Device Applications ◽  
Sic Wafer

Growth of SiC wafer material, of heterostructures with alternating SiC crystal modifications (polytypes), and of oxide layers on SiC are of importance for potential electronic device applications. By investigation of hexagonal SiC surfaces the importance of atomic surface structure for control of the respective growth processes involved is elucidated. Different reconstruction phases prepared by ex situ hydrogen treatment or by Si deposition and annealing in vacuum were analyzed using scanning tunneling microscopy (STM), Auger electron spectroscopy (AES) and low-energy electron diffraction (LEED) crystallography. The extremely efficient dangling bond saturation of the SiC(0001)-(3×3) phase allows step flow growth for monocrystalline homoepitaxial layers. A switch to cubic layer stacking can be induced on hexagonal SiC(0001) samples when a [Formula: see text] phase is prepared. This might serve as seed for polytype heterostructures. Finally, we succeeded in preparing an epitaxially well matching silicon oxide monolayer with [Formula: see text] periodicity on both SiC(0001) and SiC[Formula: see text]. This initial layer promises to facilitate low defect density oxide films for MOS devices.

scholarly journals The effect of moiré superstructures on topological edge states in twisted bismuthene homojunctions

2020 ◽  
Vol 6 (23) ◽  
pp. eaba2773 ◽  
Author(s):  
Jian Gou ◽  
Longjuan Kong ◽  
Xiaoyue He ◽  
Yu Li Huang ◽  
Jiatao Sun ◽  
...  
Keyword(s):  
Single Layer ◽  
Scanning Tunneling ◽  
Edge States ◽  
First Principles Calculations ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Spatially Distributed ◽  
Topological States ◽  
Device Applications

Creating and controlling the topological properties of two-dimensional topological insulators is essential for spintronic device applications. Here, we report the successful growth of bismuth homostructure consisting of monolayer bismuthene and single-layer black phosphorus–like Bi (BP-Bi) on the HOPG surface. Combining scanning tunneling microscopy/spectroscopy with noncontact atomic force microscopy, moiré superstructures with twist angles in the bismuth homostructure and the modulation of topological edge states of bismuthene were observed and studied. First-principles calculations reproduced the moiré superlattice and indicated that the structure fluctuation is ascribed to the stacking modes between bismuthene and BP-Bi, which induce spatially distributed interface interactions in the bismuth homostructure. The modulation of topological edge states is directly related to the variation of interlayer interactions. Our results suggest a promising pathway to tailor the topological states through interfacial interactions.

Relating Surface Structure and Growth Mode of γ′Fe4N

2003 ◽  
Vol 10 (02n03) ◽  
pp. 405-411 ◽  
Author(s):  
D. O. Boerma ◽  
S. Y. Grachev ◽  
D. M. Borsa ◽  
R. Miranda ◽  
J. M. Gallego
Keyword(s):  
Growth Mechanism ◽  
Plasma Source ◽  
Thin Layers ◽  
Scanning Tunneling ◽  
Rf Plasma ◽  
Nitride Phase ◽  
Tunneling Microscopy ◽  
Metallic Conductor ◽  
Device Applications ◽  
Step Flow Growth

We have grown thin layers of γ′Fe4N on Cu(100) substrates by molecular beam epitaxy in a flow of atomic nitrogen, delivered by a radio-frequency (RF) plasma source. This nitride phase is a ferromagnetic metallic conductor and has interesting properties for device applications. In addition it has an intriguing growth mechanism. In earlier work we found that pure crystalline layers can be grown at substrate temperatures higher than 250°C, with excess nitrogen and in the presence of hydrogen.1 To gain insight into the growth mechanism, we studied the structure and composition with scanning tunneling microscopy (STM), Auger electron spectroscopy (AES), low-energy electron diffraction (LEED) and X-ray diffraction (XRD). This was done for a coverage range of Fe4N on Cu(100) between 0.5 and 30 monolayers (ML) equivalent of Fe, deposited at 400°C, or at 300°C in one case. Here a preliminary account of this study is presented. We found that at sub-ML coverage, first "depressed" (with respect to the Cu surface) islands of Fe–N are formed. Then, on top of these islands a second layer is growing. Subsequently the space between the islands is filled up by a Fe–N layer growing directly on Cu. This gives rise to a smooth surface with patches differing in height by only 0.5 Å. The following layers grow by step-flow growth. The smooth terraces still show patches with a 0.5 Å height difference. The phase is γ′Fe4N with a distorted (p4g-like) structure as observed with LEED and STM, where a p(2 × 2) symmetry is seen. The c(2 × 2) symmetry expected for γ′Fe4N is observed after growing 30 ML or more. A model for the growth mechanism based on our observations is proposed.

Surface defects on MgO thin films: Their detection using metastable impact electron spectroscopy and interaction with probe molecules

2000 ◽  
Vol 648 ◽  
Author(s):  
Jeffrey A. Stultz ◽  
Andrei Kolmakov ◽  
Xiaofeng Lai ◽  
Young Dok Kim ◽  
D. Wayne Goodman
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Electron Spectroscopy ◽  
Surface Defects ◽  
Defect Density ◽  
Thermal Quenching ◽  
Scanning Tunneling ◽  
Extended Defects ◽  
Tunneling Microscopy ◽  
Defect Sites

AbstractMgO thin films having different defect densities are explored in this study using metastable impact electron spectroscopy (MIES), ultraviolet photoelectron spectroscopy (UPS), temperature programmed desorption (TPD), and scanning tunneling microscopy (STM). Surface point defects on MgO exhibit themselves in both the MIES and UPS spectra as a feature approximately 2 eV above the valance band, whereas extended defects are only observed spectroscopically as a broadening of the O 2p band. The interaction of NO and N2O with the MgO surface as a function of surface defect density is explored. Upon adsorption on MgO thin films at 100K, both NO and N2O show the development of three features which coincide with a standard gas phase N2O spectrum. The saturation coverage of N2O from NO adsorption increases with increasing defect density, indicating that defect sites are mainly responsible for N2O formation. STM images confirm the increase of thin film defect density upon thermal quenching.

Growth and Magnetic Properties of La0.65Pb0.35MnO3 Films

1999 ◽  
Vol 602 ◽  
Author(s):  
Q. L. Xu ◽  
M. T. Liu ◽  
Y. Liu ◽  
C. N. Borca ◽  
H. Dulli ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Defect Density ◽  
Rf Magnetron Sputtering ◽  
Scanning Tunneling ◽  
X Ray Diffraction ◽  
Tunneling Microscopy ◽  
X Ray ◽  
Bulk Magnetization ◽  
Low Energy Electron ◽  
Diffraction Patterns

AbstractWe have successfully grown La0.65PbO.35MnO3 thin films by a RF magnetron sputtering method onto (100) LaAlO3 single crystal substrates. X-ray diffraction measurements are consistent with a (100) cubic orientation of the films. The fourfold symmetry showed by LEED(Low Energy Electron Diffraction) patterns indicate that the films have surface order. STM(Scanning Tunneling Microscopy) measurements indicate that the surface of the films were smooth, with approximate 5 nm roughness. XPS (X-ray Photoemission Spectroscopy) shows that the surface defect density in the films is comparatively low. The bulk magnetization of the films at 6K in 1 T magnetic field reached 77 emu/g and a Curie temperature near 354 K, close to maximum resistivity. A negative magnetoresistance of 47% was observed at 320K in 5.5 T magnetic field.

scholarly journals Probing Electronic Properties of Graphene on the Atomic Scale by Scanning Tunneling Microscopy and Spectroscopy

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Li Gao
Keyword(s):  
Silicon Carbide ◽  
Boron Nitride ◽  
Silicon Dioxide ◽  
Scanning Tunneling Microscopy ◽  
Electronic Properties ◽  
Crucial Role ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Device Applications

AbstractAtomic scale investigations of the electronic properties of graphene are playing a crucial role in understanding and tuning the exotic properties of this material for its potential device applications. Scanning tunneling microscopy (STM) and spectroscopy (STS) are unique techniques for atomic scale investigations and have been extensively used in graphene research. In this article, we review recent progresses in STM and STS studies of the electronic properties of suspended graphene as well as graphene supported by different substrates including graphite, metals, silicon carbide, silicon dioxide and boron nitride.

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