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Atomic force microscopy investigation of the kinetic growth mechanisms of sputtered nanostructured Au film on mica: towards a nanoscale morphology control.

Ruffino F, Torrisi V, Marletta G, Grimaldi MG - Nanoscale Res Lett (2011)

Bottom Line: Furthermore, we observed that the late stage of cluster growth is accompanied by the formation of circular depletion zones around the largest clusters.From the quantification of the evolution of the size of these zones, the Au surface diffusion coefficient was evaluated in D(T) = [(7.42 × 10-13) ± (5.94 × 10-14) m2/s]exp(-(0.33±0.04) eVkT).As a consequence we acquired a methodology to control the morphological characteristics of the Au film simply controlling the annealing temperature and time.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory for Molecular Surface and Nanotechnology (LAMSUN), Department of Chemical Sciences-University of Catania and CSGI, Viale A, Doria 6, 95125, Catania, Italy. vanna.torrisi@gmail.com.

ABSTRACT
The study of surface morphology of Au deposited on mica is crucial for the fabrication of flat Au films for applications in biological, electronic, and optical devices. The understanding of the growth mechanisms of Au on mica allows to tune the process parameters to obtain ultra-flat film as suitable platform for anchoring self-assembling monolayers, molecules, nanotubes, and nanoparticles. Furthermore, atomically flat Au substrates are ideal for imaging adsorbate layers using scanning probe microscopy techniques. The control of these mechanisms is a prerequisite for control of the film nano- and micro-structure to obtain materials with desired morphological properties. We report on an atomic force microscopy (AFM) study of the morphology evolution of Au film deposited on mica by room-temperature sputtering as a function of subsequent annealing processes. Starting from an Au continuous film on the mica substrate, the AFM technique allowed us to observe nucleation and growth of Au clusters when annealing process is performed in the 573-773 K temperature range and 900-3600 s time range. The evolution of the clusters size was quantified allowing us to evaluate the growth exponent 〈z〉 = 1.88 ± 0.06. Furthermore, we observed that the late stage of cluster growth is accompanied by the formation of circular depletion zones around the largest clusters. From the quantification of the evolution of the size of these zones, the Au surface diffusion coefficient was evaluated in D(T) = [(7.42 × 10-13) ± (5.94 × 10-14) m2/s]exp(-(0.33±0.04) eVkT). These quantitative data and their correlation with existing theoretical models elucidate the kinetic growth mechanisms of the sputtered Au on mica. As a consequence we acquired a methodology to control the morphological characteristics of the Au film simply controlling the annealing temperature and time.

No MeSH data available.


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Plot (dots), in semi-log scale, of the Au surface diffusion coefficient as a function of the inverse of the temperature. The continuous line is the fit.
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Figure 12: Plot (dots), in semi-log scale, of the Au surface diffusion coefficient as a function of the inverse of the temperature. The continuous line is the fit.

Mentions: By the AFM analyses we can, also, quantify the evolution of the radius l of the depletion zones observable in the AFM images around the larger clusters. Also in this case we can proceed to a statistical evaluation of 〈l〉: by the analyses of the AFM images we obtain the distributions of l as a function of the annealing time t for each fixed annealing temperature T. Figure 10 reports, for examples, the distributions of l for the samples annealed at 773 K-1800 s (a), 773 K-2400 s (b), 773 K-3000 s (c), and 773 K-3600 s (d), respectively. Each distribution was calculated on a statistical population of 100 grains and fitted (continuous lines in Figure 10) by a Gaussian function whose peak position was taken as the mean value 〈l〉 and whose full width at half maximum as the deviation on such value. Therefore, we obtain the evolution of the mean clusters height 〈l〉 as a function of t for each fixed T. In Figure 11, we plot (dots) in a semi-log scale 〈l〉2 as a function of t for each T, obtaining linear relations as prescribed by Equation 3. Fitting the experimental data by 〈l〉2 = Dst we obtain, as fit parameter, the values of the atomic Au surface diffusion coefficient DS: DS(573 K) = (9.35 × 10-16) ± (5.6 × 10-17) m2/s, DS(673 K) = (2.55 × 10-15) ± (1.8 × 10-16) m2/s, DS(773 K) = (5.25 × 10-15) ± (3.2 × 10-16) m2/s. The Arrhenius plot of the resulting Ds(T), showen in Figure 12 indicates the occurrence of the thermally activated diffusion process [6,49] described by


Atomic force microscopy investigation of the kinetic growth mechanisms of sputtered nanostructured Au film on mica: towards a nanoscale morphology control.

Ruffino F, Torrisi V, Marletta G, Grimaldi MG - Nanoscale Res Lett (2011)

Plot (dots), in semi-log scale, of the Au surface diffusion coefficient as a function of the inverse of the temperature. The continuous line is the fit.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211157&req=5

Figure 12: Plot (dots), in semi-log scale, of the Au surface diffusion coefficient as a function of the inverse of the temperature. The continuous line is the fit.
Mentions: By the AFM analyses we can, also, quantify the evolution of the radius l of the depletion zones observable in the AFM images around the larger clusters. Also in this case we can proceed to a statistical evaluation of 〈l〉: by the analyses of the AFM images we obtain the distributions of l as a function of the annealing time t for each fixed annealing temperature T. Figure 10 reports, for examples, the distributions of l for the samples annealed at 773 K-1800 s (a), 773 K-2400 s (b), 773 K-3000 s (c), and 773 K-3600 s (d), respectively. Each distribution was calculated on a statistical population of 100 grains and fitted (continuous lines in Figure 10) by a Gaussian function whose peak position was taken as the mean value 〈l〉 and whose full width at half maximum as the deviation on such value. Therefore, we obtain the evolution of the mean clusters height 〈l〉 as a function of t for each fixed T. In Figure 11, we plot (dots) in a semi-log scale 〈l〉2 as a function of t for each T, obtaining linear relations as prescribed by Equation 3. Fitting the experimental data by 〈l〉2 = Dst we obtain, as fit parameter, the values of the atomic Au surface diffusion coefficient DS: DS(573 K) = (9.35 × 10-16) ± (5.6 × 10-17) m2/s, DS(673 K) = (2.55 × 10-15) ± (1.8 × 10-16) m2/s, DS(773 K) = (5.25 × 10-15) ± (3.2 × 10-16) m2/s. The Arrhenius plot of the resulting Ds(T), showen in Figure 12 indicates the occurrence of the thermally activated diffusion process [6,49] described by

Bottom Line: Furthermore, we observed that the late stage of cluster growth is accompanied by the formation of circular depletion zones around the largest clusters.From the quantification of the evolution of the size of these zones, the Au surface diffusion coefficient was evaluated in D(T) = [(7.42 × 10-13) ± (5.94 × 10-14) m2/s]exp(-(0.33±0.04) eVkT).As a consequence we acquired a methodology to control the morphological characteristics of the Au film simply controlling the annealing temperature and time.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory for Molecular Surface and Nanotechnology (LAMSUN), Department of Chemical Sciences-University of Catania and CSGI, Viale A, Doria 6, 95125, Catania, Italy. vanna.torrisi@gmail.com.

ABSTRACT
The study of surface morphology of Au deposited on mica is crucial for the fabrication of flat Au films for applications in biological, electronic, and optical devices. The understanding of the growth mechanisms of Au on mica allows to tune the process parameters to obtain ultra-flat film as suitable platform for anchoring self-assembling monolayers, molecules, nanotubes, and nanoparticles. Furthermore, atomically flat Au substrates are ideal for imaging adsorbate layers using scanning probe microscopy techniques. The control of these mechanisms is a prerequisite for control of the film nano- and micro-structure to obtain materials with desired morphological properties. We report on an atomic force microscopy (AFM) study of the morphology evolution of Au film deposited on mica by room-temperature sputtering as a function of subsequent annealing processes. Starting from an Au continuous film on the mica substrate, the AFM technique allowed us to observe nucleation and growth of Au clusters when annealing process is performed in the 573-773 K temperature range and 900-3600 s time range. The evolution of the clusters size was quantified allowing us to evaluate the growth exponent 〈z〉 = 1.88 ± 0.06. Furthermore, we observed that the late stage of cluster growth is accompanied by the formation of circular depletion zones around the largest clusters. From the quantification of the evolution of the size of these zones, the Au surface diffusion coefficient was evaluated in D(T) = [(7.42 × 10-13) ± (5.94 × 10-14) m2/s]exp(-(0.33±0.04) eVkT). These quantitative data and their correlation with existing theoretical models elucidate the kinetic growth mechanisms of the sputtered Au on mica. As a consequence we acquired a methodology to control the morphological characteristics of the Au film simply controlling the annealing temperature and time.

No MeSH data available.


Related in: MedlinePlus