(497a) Chemical Vapor Deposition of Copper: Study of Gas Phase Nucleation

Copper oxide has demonstrated potential for solar hydrogen production in photoelectrochemical cells [1]. Copper oxide electrodes can be produced by chemical vapor deposition (CVD) which is one of the most widely used processes for semiconductor layer fabrication.  

Previous copper oxide CVD studies [2,3] have revealed unexpected film deposition spatial patterns and temperature/oxygen partial pressure dependencies. In earlier work [4] we have statistically determined such dependencies through a surface response analysis. Furthermore, we developed a two-dimensional precursor transport model combined with overall surface and gas phase reactions to investigate the main deposition process in a hot wall reactor. Our findings suggested that the deposition process is governed by surface reactions, as opposed to the gas phase particle formation mechanism published in [2].   

In this paper we investigate the gas phase formation of small particles of copper that would eventually be the seed for oxidation and growth on the gas phase. We develop an aerosol dynamics model based on a discrete solution of the general dynamics equation, of the same type as the ones presented by Zachariah and Mukherjee in [5,6]. Our goal in this part of the study is to compare the size distribution and time scale yielded by simulations with estimates from SEM images of deposited films, to determine the existence or non existence of particle clusters on the gas phase.  

Once the dominant mechanism is identified, the gas phase model will be coupled with a kinetic Monte Carlo simulation of the surface growth to have a complete characterization of the deposition process at the macroscopic and microscopic scales. Our ultimate goal is to integrate the complete model with a photoelectrochemical cell performance model to aid in the design and optimization of electrode manufacturing.  

References
[1] Davide Barreca, Paolo Fornasiero, Alberto Gasparotto, Valentia Gombac, Chiara Maccato, Tiziano Montini, and Eugenio Tondeloo, The Potential of Supported Cu2O and CuO Nanosystems in Photocatalytic H2 Production, ChemSusChem, 2, 230-233, 2009.

[2] Lu-Sheng Hong and Hiroshi Komiyama, Chemical Vapor Deposition of CuOx Films by CuI and O2: Role of Cluster Formation on Film Morphology, J. Am. Ceram. Soc., 74(7), 1597-1604, 1991.

[3] Mikael Ottosson, Jan-Otto Carlsson, Chemical vapour deposition of Cu20 and CuO from CuI and 0 2 or N20, Surface and Coatings Technology, 78, 263-273, 1996

[4] David Arana-Chavez, Edward Toumayan, Federico Lora, Christopher McCaslin, and Raymond A. Adomaitis, Modeling the Transport and Reaction Mechanisms of Copper Oxide CVD, Chem. Vap. Deposition, 16, 336-345, 2010.

[5] A. Prakash, A. P. Bapat, and M. R. Zachariah. A Simple Numerical Algorithm and Software for Solution of Nucleation, Surface Growth, and Coagulation Problems. Aerosol Science and Technology, 37, 892-898, 2003.

[6] D. Mukherjee, A. Prakash, and M.R. Zachariah, Implementation of a discrete nodal model to probe the effect of size-dependent surface tension on nanoparticle formation and growth, Aerosol Science, 37, 1388-1399, 2006.