The wet chemical processing opens the way to deposit thin film with the versatility and ease for a variety of materials. Liquid film deposition involves the application of a liquid precursor on a substrate which is then converted to the required coating material in a subsequent post-treatment step. Different non-vacuum solution based deposition techniques have been developed to grow thin films with high efficiency and functionality. Spin coating is one of an effective technique for thin film fabrication due to low cost, uniformity, less hazardous, and capability of easy scaling up. The typical process involves depositing a small amount of a fluid onto the center of a substrate and then spinning the substrate at high speed. Dip coating is another simple, cost effective route with feasibility to scale-up for commercial production. The dip coating process can be divided into three important technical stages, immersion, withdrawal and evaporation. The coating may be subjected to further heat treatment in order to burn out residual compounds and induce crystallization of the functional oxides. Spray coating is a promising technique to grow thin film in research and industry to prepare thin and thick films. It is an easy approach to fabricate thin film with uniform distribution at small scale from a few nanometers to micrometers in thickness. Inkjet printing is the emerging promising technique to develop large-scale, and flexible thin films. The inkjet printing process allow easy customization to grow variety of complex structures.
Visible emission from Er-doped SnO2 thin films deposited by sol-gel