GROWTH OF PERCOLATED Ag NANOSTRUCTURES ON Si(111)-(7 × 7) SURFACES

2011 ◽  
Vol 10 (01n02) ◽  
pp. 123-127
Author(s):  
D. K. GOSWAMI ◽  
A. PAL
Keyword(s):  
Statistical Analysis ◽  
Surface Morphology ◽  
Room Temperature ◽  
Atomic Layer ◽  
Atomic Scale ◽  
Growth Exponent ◽  
Scanning Tunneling ◽  
Scaling Exponent ◽  
Scaling Exponents ◽  
Growth Scaling

Growth of Ag nanostructures on Si (111)-7 × 7 surfaces has been investigated at the atomic scale regime by studying the evolution of nanoscale surface morphology with Ag coverage. Ag growth on Si (111)-7 × 7 surfaces at room temperature showed a strongly preferential height with even atomic layer thick flat top percolated islands. Here we report that the roughness scaling exponent α and growth scaling exponents β associated with such electronic growth mode are determined by statistical analysis of rough surfaces obtained from scanning tunneling micrograph images of Ag nanostructures grown on Si (111)-7 × 7 surfaces. Observed roughness and growth exponent for this system are 0.82±0.02 and 0.45±0.04, respectively.

Direct Nanoscale Patterning by Atomic Manipulation

1995 ◽  
Vol 380 ◽  
Author(s):  
Craig T. Salling
Keyword(s):  
Scanning Tunneling Microscope ◽  
Room Temperature ◽  
Atomic Layer ◽  
Sample Surface ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Nanoscale Patterning ◽  
Direct Patterning ◽  
Scale Structures ◽  
Atomic Manipulation

ABSTRACTThe ability to create atomic-scale structures with the scanning tunneling microscope (STM) plays an important role in the development of a future nanoscale technology. I briefly review the various modes of STM-based fabrication and atomic manipulation. I focus on using a UHV-STM to directly pattern the Si(001) surface by atomic manipulation at room temperature. By carefully adjusting the tip morphology and pulse voltage, a single atomic layer can be removed from the sample surface to define features one atom deep. Segments of individual dimer rows can be removed to create structures with atomically straight edges and with lateral features as small as one dimer wide. Trenches ∼3 nm wide and 2–3 atomic layers deep can be created with less stringent control of patterning parameters. Direct patterning provides a straightforward route to the fabrication of nanoscale test structures under UHV conditions of cleanliness.

scholarly journals Robust procedure for creating and characterizing the atomic structure of scanning tunneling microscope tips

2017 ◽  
Vol 8 ◽  
pp. 2389-2395 ◽  
Author(s):  
Sumit Tewari ◽  
Koen M Bastiaans ◽  
Milan P Allan ◽  
Jan M van Ruitenbeek
Keyword(s):  
Atomic Structure ◽  
Scanning Tunneling Microscope ◽  
Critical Role ◽  
Atomic Layer ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Tunneling Microscope ◽  
Stm Tips

Scanning tunneling microscopes (STM) are used extensively for studying and manipulating matter at the atomic scale. In spite of the critical role of the STM tip, procedures for controlling the atomic-scale shape of STM tips have not been rigorously justified. Here, we present a method for preparing tips in situ while ensuring the crystalline structure and a reproducibly prepared tip structure up to the second atomic layer. We demonstrate a controlled evolution of such tips starting from undefined tip shapes.

Effect of Surface Segregation on the Temperature Dependence of Ion-Bombardment Induced Surface Morphology

1998 ◽  
Vol 527 ◽  
Author(s):  
B. Aufray ◽  
H. Giordano ◽  
V. Petrova ◽  
D. N. Seidman
Keyword(s):  
Surface Morphology ◽  
Heating Rate ◽  
Point Defects ◽  
Room Temperature ◽  
Surface Segregation ◽  
Elevated Temperatures ◽  
Rapid Heating ◽  
Ion Bombardment ◽  
Scanning Tunneling ◽  
Near Surface

ABSTRACTWe present a scanning tunneling microscopy (STM) study, performed at different elevated temperatures, on the influence of Sb surface segregation on the morphology of the (111) surface of a Cu-0.45 at.% Sb solid-solution single-crystal; the surface was initially cleaned at room temperature by Ar+ ion sputtering. Unexpectedly, when the temperature is increased from room temperature to 380°C, the typical (111) surface morphology, obtained after sputtering, evolves in two very different manners that depend on the heating rate. If the heating rate is rapid (approximately a few minutes), it evolves to a structure with large terraces, whereas if it is slow (about 10 hours) the morphology does not evolve -- i.e., it is frozen. These unexpected results are interpreted in terms of excess subsurface point defects (vacancies and self-interstitials) created during ion bombardment, which are mobile and can mediate Sb diffusion at low temperatures. This is mainly on step edges, but the point defects can precipitate out of solution, for a rapid heating rate, thereby forming small secondary clusters in the near-surface region, in which Sb atoms are trapped.

Scanning Tunneling Microscopy Study of the Dynamic Scaling Properties of Rough Vapor-Deposited Silver Films

1993 ◽  
Vol 317 ◽  
Author(s):  
G. Palasantzas ◽  
J. Krim
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Room Temperature ◽  
Microscopy Study ◽  
Scanning Tunneling ◽  
Dynamic Scaling ◽  
Tunneling Microscopy ◽  
Scaling Exponents ◽  
Silver Films ◽  
Scaling Properties ◽  
Roughness Exponent

ABSTRACTWe investigated the scaling behaviour of vapor-deposited silver films at room temperature by means of scanning tunneling Microscopy. The film-thickness range was ≈ 10 – 1000 nm. The roughness exponent H is observed to be H = 0.82 ± 0.05. The growth and dynamic scaling exponents are respectively observed to be β = 0.29 ± 0.06, and z = 2.53 ±0.50.

scholarly journals Adaptive diversification of growth allometry in the plant Arabidopsis thaliana

2018 ◽  
Vol 115 (13) ◽  
pp. 3416-3421 ◽  
Author(s):  
François Vasseur ◽  
Moises Exposito-Alonso ◽  
Oscar J. Ayala-Garay ◽  
George Wang ◽  
Brian J. Enquist ◽  
...  
Keyword(s):  
Growth Rate ◽  
Arabidopsis Thaliana ◽  
Abiotic Stress ◽  
Seed Production ◽  
Stress Resistance ◽  
Allometric Scaling ◽  
Hydrodynamic Resistance ◽  
Scaling Exponent ◽  
Scaling Exponents ◽  
Growth Scaling

Seed plants vary tremendously in size and morphology; however, variation and covariation in plant traits may be governed, at least in part, by universal biophysical laws and biological constants. Metabolic scaling theory (MST) posits that whole-organismal metabolism and growth rate are under stabilizing selection that minimizes the scaling of hydrodynamic resistance and maximizes the scaling of resource uptake. This constrains variation in physiological traits and in the rate of biomass accumulation, so that they can be expressed as mathematical functions of plant size with near-constant allometric scaling exponents across species. However, the observed variation in scaling exponents calls into question the evolutionary drivers and the universality of allometric equations. We have measured growth scaling and fitness traits of 451 Arabidopsis thaliana accessions with sequenced genomes. Variation among accessions around the scaling exponent predicted by MST was correlated with relative growth rate, seed production, and stress resistance. Genomic analyses indicate that growth allometry is affected by many genes associated with local climate and abiotic stress response. The gene with the strongest effect, PUB4, has molecular signatures of balancing selection, suggesting that intraspecific variation in growth scaling is maintained by opposing selection on the trade-off between seed production and abiotic stress resistance. Our findings suggest that variation in allometry contributes to local adaptation to contrasting environments. Our results help reconcile past debates on the origin of allometric scaling in biology and begin to link adaptive variation in allometric scaling to specific genes.

scholarly journals First-Principle Prediction on STM Tip Manipulation of Ti Adatom on Two-Dimensional Monolayer YBr3

Scanning ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Pan Liu ◽  
Maokun Wu ◽  
Hui Liu ◽  
Feng Lu ◽  
Wei-Hua Wang ◽  
...  
Keyword(s):  
Surface Science ◽  
Room Temperature ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
First Principle ◽  
Tunneling Microscopy ◽  
First Principle Calculations ◽  
Theoretical Predictions ◽  
Scale Characterization ◽  
Tungsten Tip

Scanning tunneling microscopy (STM) is an important tool in surface science on atomic scale characterization and manipulation. In this work, Ti adatom manipulation is theoretically simulated by using a tungsten tip (W-tip) in STM based on first-principle calculations. The results demonstrate the possibility of inserting Ti adatoms into the atomic pores of monolayer YBr3, which is thermodynamically stable at room temperature. In this process, the energy barriers of vertical and lateral movements of Ti are 0.38 eV and 0.64 eV, respectively, and the Ti atoms are stably placed within YBr3 by >1.2 eV binding energy. These theoretical predictions provide an insight that it is experimentally promising to manipulate Ti adatom and form artificially designed 2D magnetic materials.

scholarly journals Atom-vacancy hopping in ultra-high vacuum at room temperature in SrTiO3 (001)

2021 ◽  
Vol 127 (2) ◽  
Author(s):  
Rasheed Atif
Keyword(s):  
Room Temperature ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Oxide Electronics ◽  
Low Temperature Annealing ◽  
Unstable Surface ◽  
Higher Temperature ◽  
Reconstructed Surface

Abstract The diffusion at atomic scale is of considerable interest as one of the critical processes in growth and evaporation as well as a probe of the forces at an atomically flat reconstructed surface. This atomic-scale migration is critical to investigate in strontium titanate (SrTiO3) as it possesses the same status in oxide electronics as does silicon in ordinary electronics based on elemental semiconductors. Here we show that (001) terminated SrTiO3 reconstructed surface is atomically unstable enough to allow atom-vacancy hopping at room temperature. In this work, SrTiO3 (001) single crystal (7 × 2 × 0.5 mm) was sputtered (0.5 keV, 2.5 µA, 10 min) and annealed multiple times in ultra-high vacuum (UHV) and imaged using scanning tunneling microscope (STM). A relatively unstable surface was observed at low-temperature annealing and tip–surface interactions caused dislocation of mass at the surface. Both square and zig-zag nanolines were observed with atomic resolution where an atom-vacancy hopping was observed in a square diline while imaging at room temperature. The hopping was ceased when sample was annealed at higher temperature and a more compact network of nanolines was achieved. Graphic abstract

Resolution in the scanning tunneling microscope

1991 ◽  
Vol 49 ◽  
pp. 488-489
Author(s):  
R. J. Wilson ◽  
D. D. Chambliss ◽  
S. Chiang ◽  
V. M. Hallmark
Keyword(s):  
Scanning Tunneling Microscope ◽  
Fundamental Principle ◽  
Atomic Scale ◽  
Lateral Resolution ◽  
Scanning Tunneling ◽  
Electronic Noise ◽  
Vertical Resolution ◽  
Tunneling Microscopy ◽  
Spatial Profile ◽  
Theoretical Analyses

Scanning tunneling microscopy (STM) has been used for many atomic scale observations of metal and semiconductor surfaces. The fundamental principle of the microscope involves the tunneling of evanescent electrons through a 10Å gap between a sharp tip and a reasonably conductive sample at energies in the eV range. Lateral and vertical resolution are used to define the minimum detectable width and height of observed features. Theoretical analyses first discussed lateral resolution in idealized cases, and recent work includes more general considerations. In all cases it is concluded that lateral resolution in STM depends upon the spatial profile of electronic states of both the sample and tip at energies near the Fermi level. Vertical resolution is typically limited by mechanical and electronic noise.

Scanning tunneling microscopy of polymers: A status report

1989 ◽  
Vol 47 ◽  
pp. 330-331
Author(s):  
P.E. Russell ◽  
I.H. Musselman
Keyword(s):  
High Resolution ◽  
Scanning Tunneling Microscopy ◽  
Sample Surface ◽  
Atomic Scale ◽  
Constant Current ◽  
Scanning Tunneling ◽  
Status Report ◽  
Tunneling Microscopy ◽  
Research Issues ◽  
Wide Range

Scanning tunneling microscopy (STM) has evolved rapidly in the past few years. Major developments have occurred in instrumentation, theory, and in a wide range of applications. In this paper, an overview of the application of STM and related techniques to polymers will be given, followed by a discussion of current research issues and prospects for future developments. The application of STM to polymers can be conveniently divided into the following subject areas: atomic scale imaging of uncoated polymer structures; topographic imaging and metrology of man-made polymer structures; and modification of polymer structures. Since many polymers are poor electrical conductors and hence unsuitable for use as a tunneling electrode, the related atomic force microscopy (AFM) technique which is capable of imaging both conductors and insulators has also been applied to polymers.The STM is well known for its high resolution capabilities in the x, y and z axes (Å in x andy and sub-Å in z). In addition to high resolution capabilities, the STM technique provides true three dimensional information in the constant current mode. In this mode, the STM tip is held at a fixed tunneling current (and a fixed bias voltage) and hence a fixed height above the sample surface while scanning across the sample surface.

Development of the UHV-STM

1990 ◽  
Vol 48 (1) ◽  
pp. 322-323
Author(s):  
M. Iwatsuki ◽  
S. Kitamura ◽  
A. Mogami
Keyword(s):  
Surface Science ◽  
Real Space ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Great Promise ◽  
Force Microscopy ◽  
Atomic Force ◽  
Stm Image ◽  
Surface Construction ◽  
Very High

Since Binnig, Rohrer and associates observed real-space topographic images of Si(111)-7×7 and invented the scanning tunneling microscope (STM),1) the STM has been accepted as a powerful surface science instrument.Recently, many application areas for the STM have been opened up, such as atomic force microscopy (AFM), magnetic force microscopy (MFM) and others. So, the STM technology holds a great promise for the future.The great advantages of the STM are its high spatial resolution in the lateral and vertical directions on the atomic scale. However, the STM has difficulty in identifying atomic images in a desired area because it uses piezoelectric (PZT) elements as a scanner.On the other hand, the demand to observe specimens under UHV condition has grown, along with the advent of the STM technology. The requirment of UHV-STM is especially very high in to study of surface construction of semiconductors and superconducting materials on the atomic scale. In order to improve the STM image quality by keeping the specimen and tip surfaces clean, we have built a new UHV-STM (JSTM-4000XV) system which is provided with other surface analysis capability.

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