Study of Pb diffusion on Si(111)−(7×7) with scanning tunneling microscopy: Low coverage

2000 ◽  
Vol 18 (3) ◽  
pp. 1151 ◽  
Author(s):  
J. Slezak ◽  
V. Chab ◽  
Z. Chvoj ◽  
P. Mutombo
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Low Coverage

Characterization of Epitaxial Fe on GaAs(110) by Scanning Tunneling Microscopy

1989 ◽  
Vol 151 ◽  
Author(s):  
R. A. Dragoset ◽  
P. N. First ◽  
Joseph A. Stroscio ◽  
D. T. Pierce ◽  
R. J. Celotta
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Lattice Mismatch ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Small Lattice ◽  
Low Coverage ◽  
Substrate Temperatures ◽  
Stm Images ◽  
Interesting System

ABSTRACTIron on GaAs(110) comprises an interesting system not only due to small lattice mismatch, 1.4%, but also because of the magnetic properties of the overlayer. In the present work, scanning tunneling microscopy (STM) was used to investigate bcc Fe films in the 0.1 Å to 20 Å thickness range, grown at 300 K and 450 K substrate temperatures. STM images show Volmer-Weber growth with the formation of 3-D Fe islands 20–30 Å in diameter for 0.1–1 Å deposition at 300 K, increasing to 40–50 Å for thicker films. Iron island sizes at low coverage and thin film roughness at higher coverages both show significant dependence upon growth temperature.

THE LOW COVERAGE PHASES OF Pb ON Ge(001): SCANNING TUNNELING MICROSCOPY AND FIRST PRINCIPLES

2002 ◽  
Vol 09 (05n06) ◽  
pp. 1809-1814
Author(s):  
NOBORU TAKEUCHI ◽  
G. FALKENBERG ◽  
R. L. JOHNSON
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Packing Density ◽  
First Principles ◽  
Density Functional ◽  
The Other ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Experimental Bias ◽  
Low Coverage ◽  
Stm Images

Using scanning tunneling microscopy and first principles total energy calculations, we have studied the atomic structure of the low coverage phases of Pb on Ge(001): the (2 × 2) and the c(4 × 8)- α reconstructions. Based on the analysis of the experimental bias-dependent STM images and supported by the ab initio pseudopotential density-functional calculations, we present models for each structure. In both cases, there is a coexistence of Ge and Pb dimers. The (2 × 2) phase is formed by asymmetric Pb dimers parallel and in the trenches between the underlying Ge dimers. The Pb coverage is 0.5 ML and it corresponds to the maximum packing density of Pb dimers without breaking Ge dimers. The c(4 × 8) - α reconstruction has a Pb coverage of 0.75 ML and it is characterized by asymmetric Pb dimers forming chains along the [110] direction. However, in this case half of the Ge dimers are broken. The other half remain intact and they are perpendicular to the Pb dimers.

Low-coverage, low-temperature phase of Al overlayers on the Si(111) α-7×7 structure observed by scanning tunneling microscopy

1993 ◽  
Vol 47 (20) ◽  
pp. 13930-13932 ◽  
Author(s):  
Masamichi Yoshimura ◽  
Katsuya Takaoka ◽  
Takafumi Yao ◽  
Tomoshige Sato ◽  
Takashi Sueyoshi ◽  
...  
Keyword(s):  
Low Temperature ◽  
Scanning Tunneling Microscopy ◽  
Scanning Tunneling ◽  
Temperature Phase ◽  
Tunneling Microscopy ◽  
Low Coverage ◽  
Low Temperature Phase

A study on α-RuCl3 crystal structure by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 30-31
Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele
Keyword(s):  
Crystal Structure ◽  
Density Distribution ◽  
Scanning Tunneling Microscopy ◽  
Electron Density ◽  
Structure Determination ◽  
Electron Density Distribution ◽  
Scanning Tunneling ◽  
Monoclinic Space Group ◽  
Tunneling Microscopy ◽  
X Ray

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.

Roughness measurements of nonlinear optical polymer films by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 22-23
Author(s):  
I. H. Musselman ◽  
R.-T. Chen ◽  
P. E. Russell
Keyword(s):  
Surface Roughness ◽  
Scanning Tunneling Microscopy ◽  
Nonlinear Optical ◽  
Polymer Surface ◽  
Light Extinction ◽  
Scanning Tunneling ◽  
Silicon Substrates ◽  
Tunneling Microscopy ◽  
Optical Polymer ◽  
Total Light

Scanning tunneling microscopy (STM) has been used to characterize the surface roughness of nonlinear optical (NLO) polymers. A review of STM of polymer surfaces is included in this volume. The NLO polymers are instrumental in the development of electrooptical waveguide devices, the most fundamental of which is the modulator. The most common modulator design is the Mach Zehnder interferometer, in which the input light is split into two legs and then recombined into a common output within the two dimensional waveguide. A π phase retardation, resulting in total light extinction at the output of the interferometer, can be achieved by changing the refractive index of one leg with respect to the other using the electrooptic effect. For best device performance, it is essential that the NLO polymer exhibit minimal surface roughness in order to reduce light scattering. Scanning tunneling microscopy, with its high lateral and vertical resolution, is capable of quantifying the NLO polymer surface roughness induced by processing. Results are presented below in which STM was used to measure the surface roughness of films produced by spin-coating NLO-active polymers onto silicon substrates.

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