Nucleation Kinetics on Inhomogeneous Substrates: Al/Au(111)

Fischer, Björn; Brune, Harald; Barth, Johannes V.; Fricke, Alexander; Kern, Klaus

doi:10.1103/physrevlett.82.1732

Cited by 62 publications

(50 citation statements)

References 27 publications

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“…As we will see below, mean-®eld nucleation theory in its classical form for isotropic substrates is no longer applicable for nucleation on inhomogeneous substrates. A quantitative description therefore necessitates realistic KMC simulations [190]. In these simulations barriers for moving up dislocations are larger than those for descending from dislocations.…”

Section: Adatom Diffusion On Au(1 1 1) ± the Effect Of Dislocationsmentioning

confidence: 99%

Microscopic view of epitaxial metal growth: nucleation and aggregation

Brune

1998

Surface Science Reports

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Section: Adatom Diffusion On Au(1 1 1) ± the Effect Of Dislocationsmentioning

confidence: 99%

Microscopic view of epitaxial metal growth: nucleation and aggregation

Brune

1998

Surface Science Reports

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924

140

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“…The development of nanotechnology requires good understanding of the evolution of the shape, size and distribution of nanoparticles in different growth processes [8,9]. Nanoparticles have been commonly grown in physical [10,11] and electrochemical processes [12 -16]. In the physical deposition process, the deposition rate and surface diffusion coefficient determine the shape, size and density of the nanoparticles on a specific substrate surface [17].…”

Section: Introductionmentioning

confidence: 99%

Growth of self-assembled copper nanostructure on conducting polymer by electrodeposition

Sarkar

Zhou

Tannous

et al. 2003

Solid State Communications

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In the present work, self-assembled nanostructures of copper are grown by electrodeposition on a thin conducting polymer (polypyrrole) film electropolymerized on a gold electrode. The shapes, sizes and the densities of the nanostructures are found to depend on the thickness of the polypyrrole thin film, which provides an easy means to control the morphology of these nanostructures. In particular, for the same applied potential on the gold electrode, smaller nanocrystals with a higher density are observed on thinner polymer films while bigger nanocrystals at a lower density are found on thicker films. The generation of nanostructured materials on a surface is a new thrust in materials science due to the continuing miniaturization of electronic and mechanical devices. In general, feature sizes 30 -300 nm and larger are routinely produced by electron-beam and photolithography techniques, respectively. Important progress has been made over the past few years in the preparation of ordered ensembles of metal and semiconductor nanocrystals to fabricate feature size less than 30 nm [1,2]. Devices fabricated entirely from polymers are now available, opening up the possibility of adapting polymer processing technologies to fabricate inexpensive, large-area devices using non-lithographic techniques [3,4]. Nanostructured materials have attracted much recent attention due to their important roles in many technological areas such as heterogeneous catalysis [5], photonics [6], single electron and quantum devices [7]. The development of nanotechnology requires good understanding of the evolution of the shape, size and distribution of nanoparticles in different growth processes [8,9]. Nanoparticles have been commonly grown in physical [10,11] and electrochemical processes [12 -16]. In the physical deposition process, the deposition rate and surface diffusion coefficient determine the shape, size and density of the nanoparticles on a specific substrate surface [17]. On the other hand, the concentration and pH of the electrolyte as well as the applied potential all play a prominent role in the electrochemical deposition process [18]. The use of an STM tip to develop copper nanostructures on a single-crystal gold electrode electrochemically has also been demonstrated [19]. Two common growth modes can be defined either as progressive or instantaneous, in the electrochemical deposition process, depending on the surface energies of the substrate and the deposited materials as well as their interface energy. In the Volmer -Weber growth process, the growth mode is instantaneous due to the large difference in the surface energies of the substrate and the deposited material [20]. The number of active nucleation sites is proportional to the applied potential because the nucleation barrier becomes lower with increasing applied potential [21].Organic conducting polymers, particularly in the form of thin films, are attractive candidates for microelectronic applications [22,23] due to their unique combination of electrical, mechanical ...

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“…It is by no means a singular property for the present system. In a recent investigation of the Al͞Au͑111͒ system, we found Arrhenius behavior with a minute migration barrier ͑E m 30 6 5 meV͒ along with an even more pronounced reduction of the preexponential factor, which was determined to D 0 ഠ 5 3 10 213 cm 2 ͞s corresponding to an effective attempt frequency of n 0 2.4 3 10 3 s 21 [26]. Similar, albeit less drastic effects, exist for the migration of Ag on various fcc surfaces [18,24,27], where, with the migration barrier decreasing from 168 6 5 to 60 6 10 meV, the corresponding preexponential factor drops from the universal value D 0 1.4 3 10 2260.3 ͑n 0 7 3 10 1360.3 s 21 ͒ to D 0 2 3 10 2760.6 cm 2 ͞s ͑n 0 1 3 10 960.6 s 21 ͒.…”

mentioning

confidence: 99%

“…Similar, albeit less drastic effects, exist for the migration of Ag on various fcc surfaces [18,24,27], where, with the migration barrier decreasing from 168 6 5 to 60 6 10 meV, the corresponding preexponential factor drops from the universal value D 0 1.4 3 10 2260.3 ͑n 0 7 3 10 1360.3 s 21 ͒ to D 0 2 3 10 2760.6 cm 2 ͞s ͑n 0 1 3 10 960.6 s 21 ͒. Note that with all these systems dimer stability ͑i 1͒ and the absence of cluster mobility were ensured by investigating the onset of coarsening for dimers [24] or by analyzing the island size distributions [26].…”

mentioning

confidence: 99%

Dynamics of Surface Migration in the Weak Corrugation Regime

et al. 2000

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We report a systematic study for metal-on-metal surface migration in the weak corrugation regime, i.e., with migration barriers falling below ഠ100 meV. The migration characteristics are elucidated by variable-temperature scanning tunneling microscopy observations in the 50 -200 K temperature range, which are analyzed by means of nucleation theory. The results demonstrate that, upon entering the weak corrugation regime, the dynamics of the systems are characterized by increasingly reduced effective preexponential factors, while Arrhenius behavior prevails. PACS numbers: 68.35.Fx, 61.16.Ch, 68.35.Ja, The thermal migration of adsorbed atoms on the periodic lattice of a surface offers an ideal test case to systematically investigate the energetics and dynamics of a rate phenomenon in chemical physics. Surface migration requires the overcoming of an energy barrier E m separating two identical states, a process usually obeying an Arrhenius law [1][2][3]. In particular, the mobility of atoms on metal surfaces has been extensively studied due to its importance for a variety of processes in science and technology, such as heterogeneous catalysis or epitaxial growth [4][5][6]. The phenomenology is simple: Atoms or small molecules are preferentially adsorbed at specific highsymmetry sites of the surface periodic atomic lattice, which are separated by energy barriers being generally a mere fraction of the adsorption energy. The lateral mobility of the adspecies is driven by the substrate heat bath providing stochastic excitations whose characteristic energy is given by the Debye temperature (ϳ25 meV for metals). When the density is low, a two-dimensional random motion of isolated adspecies or tracer diffusion [5] is operational; i.e., adsorbates hop from energy minima to neighboring energy minima. This process can be adequately described in terms of transition state theory (TST) [7], when the thermal energies are much smaller than the migration barrier, i.e., k B T ø E m , and when the coupling of the adspecies to the substrate is sufficiently effective to ensure equilibration between the individual jumps. These conditions normally hold for metallic adsorbates on metal surfaces, and the corresponding tracer diffusion coefficient D ‫ء‬ is given by [5]where b 1͞k B T, a is the periodicity of the surface lattice, and n 0 is the attempt frequency, frequently associated with the lateral vibrational mode of the adatom; D 0 is the preexponential factor.The situation becomes more intricate when the thermal energy increases such that k B T ϳ E m and it is anticipated that TST breaks down, until for k B T ¿ E m a free twodimensional Brownian motion of the adatoms is expected, where the diffusivity is directly proportional to the temperature [8]. Another complication may arise when the coupling of the adatom to the substrate is weak or strong. The resulting effect is twofold: On the one hand, a decrease of the attempt frequency is expected, which lowers the mobility [9][10][11]. On the other hand, for the case of weak coupling, adspec...

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Nucleation Kinetics on Inhomogeneous Substrates: Al/Au(111)

Cited by 62 publications

References 27 publications

Microscopic view of epitaxial metal growth: nucleation and aggregation

Microscopic view of epitaxial metal growth: nucleation and aggregation

Growth of self-assembled copper nanostructure on conducting polymer by electrodeposition

Dynamics of Surface Migration in the Weak Corrugation Regime

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