Abstract— In this work, we report on the growth process of multilayer thin films based on layer by layer (LBL) deposition of engineered nanoparticles. The LBL thin films were constructed with zinc sulphide nanoparticles capped with a polyelectrolyte such as chitosan, and gold nanoparticles stabilized by electrostatic charges. The LBL process of self assembly of nanoparticle monolayers & subsequent monoparticulate layered sandwiched units were built on silanized substrates by repeating the self-organization process. We discuss the linear growth of the layers upon multiple dipping, the surface morphology of the obtained films, and the I-V characteristics with increasing film thicknesses. Index Terms— Layer by layer, Film, Multilayer, Nanoparticles, Colloid I. INTRODUCTION The method of organized assembly of macromolecules and nanoparticles is being increasingly studied for creating novel nanostructures [1]. As the assembly method is not limited to the nanometer length scales, it has a potential of leading to programmable assembly and hence overcoming the limitation of classical manufacturing techniques [2], [3]. Nanoparticles are considered by many to be the building blocks of future devices that merit the development of novel assembly strategies. Strategies using single particle manipulation and random particle deposition are being considered straightforward methods to fabricate and explore new device architectures. For example, the use of a modified scanning probe microscope to position the nanoparticles [4], [5], the use Manuscript received August 14, 2006. (This work has been partially supported by Royal Thai Government, Thailand and the Korea Institute of Science and Technology, South Korea.) * Centre of Excellence in Nanotechnology, School of Engineering and Technology, Asian Institute of Technology, P.O. Box 4, Klong Laung, Pathumthani 12120, Thailand. † National Nanotechnology Center, 111 Thailand Science Park, Pahon Yothin Rd., Klong Luang, Pathumthani 12120, Thailand ‡ The National Metals and Materials Technology Center, 114 Paholyothin Rd., Klong 1, Klong Luang, Pathumthani 12120, Thailand. †† Korea Institute of Science and Technology (KIST), 39-1 Haweolgok-dong Sungbuk-ku Seoul, Korea. ** Corresponding Author phone: +66 2 524 5680; fax: +66 2 524 5697; email: joy@ait.ac.th of nano-tweezers is for picking and placing nanoparticles [4]. All such techniques are at an early stage of development with some inherent advantages and disadvantages and sometimes unsuitable to provide required characteristics e.g. behavior of electrical properties. To overcome these disadvantages, attempts have been made and some reported in the literature to use self assembly processes to construct new devices [2–5]. The simplicity of self organization by LBL process is a promising method for the fabrication of thin films. Generally, LBL is used to assemble polyelectrolyte for engineering polymer multilayer of variable architectures and thicknesses [5]. The properties of the self-assembled multilayer depend on the choice of the building blocks used, their rational organization and integration along the axis perpendicular to the substrate. This technique is not limited to coating flat objects and the environmental benefits of the possibility of using water-based processes at reasonable costs, and the utilization of particular chemical properties of the film for further modification renders this process interesting [5], [6]. Colloidal system consisting of clusters of particles suspended in a liquid can be used to build materials by this bottom-up approach [5-8]. A prerequisite for the utilization of colloids in nanotechnology for t he fabrication of ordered thin films is that they remain in suspension and resist agglomeration or flocculation. This stability of a colloid is usually achieved by either electrostatic or steric stabilization. Electrostatic stabilization involves the creation of an electrical double layer arising from ions intentionally adsorbed on the surface of the particle and associated counter ions that surround the particle, leading to columbic repulsion between the particles preventing their agglomeration, provided that the electric potential associated with the double layer is sufficiently high. Steric hindrance is achieved by the adsorption of macromolecules such as polymers onto the surface of the particles. Two distinct effects describe this type of stabilization (the volume restriction contribution and the osmotic diffusion). First, the fact that the adsorbed molecules are restricted in motion causes a decrease in the configurationally entropic contribution to the free energy. Second, the local increase in concentration of polymer chains between approaching particles results in an osmotic repulsion, since the solvent reestablishes equilibrium by Growth Process of Novel Thin Films by Directed Self Organization of Nanoparticles S. Promnimit * , S. Pratontep † , C. Thanachayanont ‡ , J. K. Park †† and J. Dutta *, ** 1-4244-0610-2/07/$20.00 ©2007 IEEE 347 Proceedings of the 2nd IEEE International Conference on Nano/Micro Engineered and Molecular Systems January 16 - 19, 2007, Bangkok, Thailand