Nucleation and growth in the electrodeposition on n-Si(111)-H surfaces

M. J. PRIETO; G.I. LACCONI

New Hampshire, Estados Unidos

Conferencia; Gordon Research Conference on Electrodeposition.; 2006

Gordon Research Conference

NUCLEATION AND GROWTH IN ELECTRODEPOSITION OF COPPER ON n-Si(111)-H SURFACES   Mauricio J. Prieto, Gabriela I. Lacconi INFIQC, Depto. Fisicoquímica, Facultad de Ciencias Químicas ? Universidad Nacional de  Córdoba, Medina Allende y Haya de La Torre, Cdad. Universitaria. 5000 Córdoba, ARGENTINA E-mail: glacconi@mail.fcq.unc.edu.ar   Deposition of thin films of metals on semiconductors is normally performed in vacuum. The metal/semiconductor electrical contacts are very important for technological applications due to the Schottky unions and the ohmic contacts obtained by metallization. The electrochemical deposition represents an alternative to obtain deposition of thin films of metals on semiconductors surfaces. The formation of deposits requires a detailed knowledge of the nucleation and growth mechanism of the new phase and the influence of parameters such as applied potential and electrolyte composition. Recently, the mechanism of formation of metallic deposits on semiconductors as well as the analysis of the surface structure have been studied by various research groups, employing electrochemical methods and SPM techniques [1-2]. In the present work, the electrodeposition of copper on hydrogen terminated n-Si(111) surfaces from an additive-free acid bath was investigated. The j/E potentiodynamic profiles show a deposition peak characteristic of diffusion limited growth. The hydrogenation of the surface is obtained by immersion of silicon wafers in fluoride solutions. This procedure generates surfaces atomically smooth with terraces well defined. The flat band potential of n-Si(111) in copper ion free solutions was determined by capacitance measurements. The key of the process to form metallic nanostructures with good properties is the formation of nuclei. Therefore, through the analysis of the current transients obtained at different potentials is possible to establish the kinetics of nucleation and growth of the metallic crystals. The nucleus density increases linearly with time, corresponding to a progressive nucleation and 3D diffusion limited growth mechanism. Nucleation rate is obtained from the analysis of current transients at different overpotentials. Atomic force microscopy (AFM) was used to obtain the morphology of the copper crystals deposit.   1.       R.T. Poetzschke, G. Staikov, W.J. Lorenz, W. Wiesbeck, J. Electrochem. Soc. 146 (1999) 141; R. Krumm, B. Guel, C. Schmitz, G. Staikov, Electrochim. Acta, 45 (2000) 3255; K. Márquez, R. Ortiz, J.W. Schultze, O.P. Márquez, J. Márquez, G. Staikov, Electrochim. Acta,48 (2003) 711. 2.       J.C. Ziegler, R.I. Wielgosz, D.M. Kolb, Electrochim. Acta, 45 (1999) 827; J.C. Ziegler, A. Reitzle, O. Bunk, J. Zegenhagen, D.M. Kolb, Electrochim. Acta, 45 (2000) 4599.   Acknowledgements: The authors gratefully acknowledge the financial support of this work by  CONICET, FONCyT, Agencia Córdoba Ciencia S.E. y SECyT-UNC.