Film: A Synthesis Essay

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Solution growth deposition This technique consists essentially of inserting the substrate into a solution containing hydrolysable metal compounds and pulling it out at a constant speed into an atmosphere containing water vapour. In this atmosphere, hydrolysis and condensation takes place. Finally the films are hardened by a high temperature cycle to form transparent metal oxides. Any hydrolysable compound including halides or nitrates but preferably metallo-organics are suitable for this process. The important control parameters are the viscosity of the solution, the pulling speed and the firing temperature. The rate of heating also needs to be controlled to avoid cracking of the films. This technique has been used commercially …show more content…
One process to meet these criteria is chemical bath deposition .The chemical bath deposition technique involves the controlled precipitation from solution of a compound on a suitable substrate. The technique offers many advantages over the more established vapour phase synthetic routes to semiconductor materials, such as chemical vapour deposition (CVD), molecular beam epitaxy (MBE) and spray pyrolysis. Factors such as control of film thickness and deposition rate by varying the solution pH, temperature and reagent concentration are allied with the ability of chemical bath deposition to coat large areas, in a reproducible and low cost process. The chemical bath deposition process uses a controlled chemical reaction to effect the deposition of a thin film by precipitation. In the most typical experimental approach, substrates are immersed in an alkaline solution containing the chalcogenides source, the metal ion, added base and complexing agent. The latter is used to control the speciation of the metal ion. The chemical bath technique appears to be a relatively simple inexpensive method to prepare a homogeneous film with controlled composition. Chemical bath deposition has been widely applied to the fabrication of semiconductor layers for photovoltaic

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