An In Situ STM Investigation of Stranski - Krastanov Growth of Ag on Au (111) Electrodes

1993 ◽  
Vol 317 ◽  
Author(s):  
S. G. Corcoran ◽  
G. S. Chakarova ◽  
K. Sieradzki
Keyword(s):  
Heterogeneous Nucleation ◽  
Three Dimensional ◽  
Growth Front ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Diffusion Limited Aggregation ◽  
Experimental Conditions ◽  
Diffusion Limited ◽  
Ag Crystallites

ABSTRACTWe present in situ scanning tunneling Microscopy (STM) results which show the morphological aspects of Ag electrodeposition on Au (111). The experimental conditions enabled us to follow, in real time, with monolayer resolution, the morphological details of Stranski-Krastanov (SK) growth under a fixed electrochemical potential (constant supersaturation). Two epitaxial layers of Ag were sequentially formed prior to the heterogeneous nucleation of three-dimensional Ag crystallites. STM images are presented showing that the second silver monolayer has a coarsened (surface) diffusion-limited-aggregation growth front. IMMediately after the completion of the second silver monolayer which took approximately five Minutes, we observed the formation of 3D clusters preferentially at step edges. Our analysis of the SK growth process indicates that it is not well described by heterogeneous-nucleation thermodynamics owing to the almost identical lattice parameters of Ag and Au. Instead, we argue that the wetting-nonwetting transition we observed was kinetically stabilized by the relatively high activation energy involved with the motion of Ag adatoms over a descending Ag step.

Self-Assembled InAs Islands on (AI,Ga)As, an In Situ Scanning Tunneling Microscopy Study

1999 ◽  
Vol 571 ◽  
Author(s):  
P. Ballet ◽  
J.B. Smathers ◽  
G.J. Salamo
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Molecular Beam ◽  
Three Dimensional ◽  
Microscopy Study ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Self Organized ◽  
Scanning Tunneling Microscopy Study ◽  
Island Density

ABSTRACTWe report an in-situ molecular beam epitaxy – scanning tunneling microscopy study of three dimensional (3D) self organized InAs islands on (AI,Ga)As surfaces. The influence of the presence of Al atoms on the roughness of the starting surface and on the island density is shown by investigating several Al compositions. We emphasize the case of InAs/AlAs and point out the major differences between this system and the widely studied InAs/GaAs system.

DIFFERENT GROWTH BEHAVIOR OF Ge, Al AND Sb ON GRAPHITE

2006 ◽  
Vol 13 (02n03) ◽  
pp. 287-296 ◽  
Author(s):  
WENDE XIAO ◽  
ZHIJUN YAN ◽  
SUNIL SINGH KUSHVAHA ◽  
MAOJIE XU ◽  
XUE-SEN WANG
Keyword(s):  
Double Layer ◽  
Room Temperature ◽  
Pyrolytic Graphite ◽  
Three Dimensional ◽  
Growth Behavior ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Defect Sites ◽  
Unique Nature

Growth of Ge , Al and Sb on highly oriented pyrolytic graphite (HOPG) was systematically investigated using in situ scanning tunneling microscopy (STM). At room temperature (RT), three dimensional (3D) clusters of all three elements nucleate and grow at the step edges and defect sites of HOPG. The clusters of Al and Ge form chains, while Sb islands are mostly isolated. With further deposition at RT, Al clusters grow and coarsen into faceted islands with craters on the top (111) facets, whereas ramified single- and double-layer cluster islands are observed for Ge . When deposited or annealed at T ≥ 175° C , Ge forms crystallites but with randomly oriented facets. As spherical Sb islands grow beyond certain size, (111) facets appear on the top. Additionally, crystalline 2D films and 1D nanorods are observed for Sb deposited at RT. At T ≈ 100° C and higher flux, only the 2D and 1D Sb islands are formed. These different growth behaviors reflect the unique nature in which the atoms (molecules), clusters and crystallites of each element interact with HOPG surface and with each other.

STM imaging of the sample or the tip ? an in situ REM study

1992 ◽  
Vol 50 (2) ◽  
pp. 1126-1127
Author(s):  
W.K. Lo ◽  
J.C.H. Spence
Keyword(s):  
Image Interpretation ◽  
Scanning Tunneling ◽  
Image Artifacts ◽  
Imaging Method ◽  
Tunneling Microscopy ◽  
Experimental Conditions ◽  
Image Artifact ◽  
Reflection Electron Microscopy ◽  
Stm Image

Image interpretation for Scanning Tunneling Microscopy (STM) is complicated by inadequate tip characterization. Tip and surface features can be difficult to separate, especially for rough surfaces. Figure 1, an STM image of a gold platelet deposited onto graphite, illustrates some of the possible problems. The doubled image of the platelet and step, for example, is a commonly encountered image artifact caused by tunneling from multiple tip asperities. The shape of the platelet(s) may also be an artifact since they are usually round. Ordinarily, to confirm the interpretation of such objects, experiments would be repeated using different tips and specimens to test for reproducibility. This is not an ideal procedure since the exact experimental conditions are difficult to duplicate. Alternatively, by comparing images of the same topography taken by STM and an independent imaging method, one can expose these artifacts.STM image artifacts were studied using an STM operating inside a Philips EM 400T TEM. This allowed imaging of the same region by Reflection Electron Microscopy (REM) and STM, independently of each other.

Ge-Quantum Dots on SI(001) Tailored by Carbon Predeposition

1998 ◽  
Vol 533 ◽  
Author(s):  
O. Leifeld ◽  
D. Grützmacher ◽  
B. Müller ◽  
K. Kern
Keyword(s):  
Surface Roughness ◽  
Critical Thickness ◽  
Carbon Deposition ◽  
Compressive Strain ◽  
Second Step ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Island Nucleation ◽  
Facet Formation

AbstractThe morphology of Si(001) after carbon deposition of 0.05 to 0.11 monolayers (ML) was investigated in situ by ultrahigh vacuum scanning tunneling microscopy (UHV-STM). The carbon induces a c(4×4)-reconstruction of the surface. In addition, carbon increases the surface roughness compared to clean Si(001) (2×1). In a second step, the influence of the carbon induced restructuring on Ge-island nucleation was investigated. The 3D-growth sets in at considerably lower Ge coverage compared to the clean Si(001) (2×1) surface. This leads to a high density of small though irregularly shaped dots, consisting of stepped terraces, already at 2.5 ML Ge. Increasing the Ge-coverage beyond the critical thickness for facet formation, the dots show { 105 }- facets well known from Ge-clusters on bare Si(001) (2×1). However, they are flat on top with a (001)-facet showing the typical buckled Ge rows and missing dimers. This indicates that the compressive strain is not fully relaxed in these hut clusters.

Multifractal spectrum of off-lattice three-dimensional diffusion-limited aggregation

1992 ◽  
Vol 46 (6) ◽  
pp. R3016-R3019 ◽  
Author(s):  
Stefan Schwarzer ◽  
Marek Wolf ◽  
Shlomo Havlin ◽  
Paul Meakin ◽  
H. Eugene Stanley
Keyword(s):  
Three Dimensional ◽  
Multifractal Spectrum ◽  
Diffusion Limited Aggregation ◽  
Diffusion Limited ◽  
Dimensional Diffusion

Surface Structures of Phosphorus and Indium on Si(111)

1998 ◽  
Vol 05 (01) ◽  
pp. 69-76
Author(s):  
F. P. Netzer ◽  
L. Vitali ◽  
J. Kraft ◽  
M. G. Ramesy
Keyword(s):  
Elevated Temperature ◽  
Room Temperature ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Low Energy Electron Diffraction ◽  
Diffusion Limited ◽  
Lower Terrace ◽  
Surface Reconstructions ◽  
Low Energy Electron ◽  
Stm Images

The interaction of vapor phase P2 with the [Formula: see text] monolayer surface at room temperature and elevated temperature has been monitored by scanning tunneling microscopy (STM) and spectroscopy (STS) in conjunction with Auger electron spectroscopy and low-energy electron diffraction (LEED). The surface rection can be readily followed by STM because of the very different contrast of the reacted areas in the STM images. The reaction develops around overlayer defects at room temperature and appears to be diffusion-limited, whereas at 300°C the reaction is initiated at the step edges, from which the reaction front progresses onto the lower terrace areas. At elevated temperature several ordered surface reconstructions, showing different STS fingerprints, are detected on the P–In/Si(111) surfaces, which are associated tentatively with P- and Si-terminated structures and an ordered InP phase.

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