What is the rule of thumb to know the oxidation temperature of any type of metal thin film to form its corresponding oxide ?
Hai vishal , many metal thin films oxidize (native oxide) even at room temperature ex. aluminum , copper, Tin etc. If you want to deposit a oxide thin film, during the thin film deposition process you can introduce some oxygen into the chamber. you have to carefully optimize the oxygen partial pressure for the required composition of the oxide thin film.
Agreeing with the previous note: you should define what you mean by "oxidation temperature". You may define it by the thickness of the oxide layer, by the weight gain tc. within a certain time. Chemical reactions are not yes or no type phenomena, the reaction rate is temperature dependent. Oxidation of a metal surface if a heterogenous reaction, atl least one diffusion and one chemical reaction step occus subsequnetly. the slower process will determine the overall rate. The rate of the chemical reaction may be estimated form the reaction heat of the oxidation (although this is a themrodynamic quantitiy and reaction rate is a kinetic pehnomenon, determined by the activation energy) and much depends on the diffusion coefficient in the oxide layer (whether it is molecular or atomic). So there are several factors which define oxidation rate, some of them temperature dependent.
Dear Mr. Rao and Mr. Gyorgy thanks for your reply. But i think i have not made my query clear. Actually in my case i am first growing metal thin films and then post annealing in O2 environment to form their corresponding oxides. Since some of the oxides have multiple phases and if i am interested in particular phase then that will of-course depend on the oxidation temperature used. So i want to know the rules which governs the choice of this oxidation temperature.
If the process is thermodynamically controlled, and not kinetically, you will have to look for transcyrstallization temperatures, which is defined by the heat of formation at standard temperature, Cp(T) curves of the corresponding oxides and by the phase change heat. If it is kinetically controlled, overheating is possible. It may be further complicated by the presence of multiple valencies. Anyway you need good thermodynamic table and data on the relevant compounds.
Dear vishal , try to carry out annealing in the deposition chamber itself after filling with pure oxygen gas to avoid the formation of different phases from the ambient gases present in the atmosphere and please consider the Mr. Gyorgy comments regarding the how to fix the oxidation temperature..
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