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Open Access Nano Express

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

Francesco Ruffino12, Vanna Torrisi3*, Giovanni Marletta3 and Maria Grazia Grimaldi12

Author affiliations

1 Dipartimento di Fisica e Astronomia, Università di Catania via S. Sofia 64, 95123 Catania, Italy

2 CNR-IMM MATIS, via S. Sofia 64, I-95123 Catania, Italy

3 Laboratory for Molecular Surface and Nanotechnology (LAMSUN), Department of Chemical Sciences-University of Catania and CSGI, Viale A. Doria 6, 95125, Catania, Italy

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Citation and License

Nanoscale Research Letters 2011, 6:112  doi:10.1186/1556-276X-6-112

Published: 31 January 2011

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 <a onClick="popup('http://www.nanoscalereslett.com/content/6/1/112/mathml/M1','MathML',630,470);return false;" target="_blank" href="http://www.nanoscalereslett.com/content/6/1/112/mathml/M1">View MathML</a>. 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.