Synthesis of Metal Oxide Nanoparticles by Flame Method Synthesis of Metal Oxide Nanoparticles by Flame Method

Plasma Spray Process Schematic Diagram of the Plasma Spray Process

Wet Technologies for the Formation of Organic Nanostructures

Chemical methods of material processing were known for years, existing in parallel with physical methods of film deposition. Recent advances in electron microscopy and scanning nanoprobe microscopy (STM, AFM) have revealed that some of the materials produced by the chemical methods have distinctive nanocrystalline structure. Furthermore, due to the achievements of colloid chemistry in the last 20 years, a large variety of colloid nanoparticles have become available for film deposition. This has stimulated great interest in further development of chemical methods as cost-effective alternatives to such physical methods as: thermal evaporation; magnetron sputtering; chemical and physical vapor deposition (CVD, PVD); and molecular beam epitaxy (MBE). This chapter will review chemical methods of film deposition, with the emphasis on novel techniques for nanostructured materials processing.

Self-Assembly of Colloid Nanoparticles The deposition of colloid nanoparticles onto solid substrates can be accomplished by different methods, such as simple casting, electrostatic deposition, Langmuir- Blodgett, or spin coating techniques, which will be discussed in detail later in this course. However, the simplest method of nanoparticles deposition, which gives some remarkable results, is the so-called self-assembly or chemical self-assembly method. This method, which was first introduced by Netzer and Sagiv [12], is based upon strong covalent bonding of the adsorbed objects (i.e., monomer or polymer molecules and nanoparticles) to the substrate via special functional groups.

Electrodeposition of Nanostructured Materials Electrodeposition is one of the first chemical (or rather electrochemical) methods for the formation of inorganic coatings on solid surfaces. The formation of metal coatings on the anode by means of electrolysis of respective metal salts has been known since the nineteenth century. During the last few decades, this method has spread to other materials, such as II-VI and II-V semiconductor materials, with the main application in photovoltaic devices and solar cells.

The first route is more traditional, and is based on the well-developed technique of electroplating. In order to form nanostructured materials, some kind of surfactants should be added to the electrolyte solution. The surfactants act as a stabilizing agent to coat nanocrystals and to prevent them from further aggregation, and therefore the formation of large grains of material. The review papers [20, 21] present a variety of materials, including metals, semiconductors, ceramics, and polymers,deposited in this way. A classical example of gold nanoparticles deposition is given in [22]. Monodispersed gold nanoparticles of a few nanometers were fabricated and deposited simultaneously on the silicon surface by the galvanostatic reduction of HAuCl4 in the presence of dodecanethiol.

Schematic diagram of spurting machine [ 2002].

Spin Coating The method of spin coating was known for decades as a main technique for the deposition of polymer layers onto flat solid surfaces, and particularly for photoresist deposition in microelectronics fabrication. The idea is very simple, and consists of spreading of a polymer solution onto the substrate fixed on a stage, rotating at a speed in the order of thousands of revolutions per minute. Under the influence of the central force, the polymer solution spreads evenly over the large area and dries out, due to the solvent evaporation during the rotation. After additional baking at elevated temperatures, a polymer layer is finally formed on the surface.