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Rate limiting steps in metal oxide epitaxy

On the bottom right-hand side of the third page of the pdf attached (page 2 of the article), the author states:

"Metal deposition rates are easily converted into the oxide growth rate under the assumption that the metal arrival rates are the rate limiting steps, which is true for growth under oxygen- rich conditions."

I am having trouble understanding this, so please answer the following questions to clarify it for me.

(a) What is meant by metal arrival rates being "rate limiting steps?" (Does this refer to oxidation?)

(b) Why is this true? (Why are metal arrival rates rate limiting steps?)

(c) What exactly is meant by an "oxygen-rich environment?" I haven't seen a technical definition of an "oxygen-rich environment" anywhere in the literature.


Solution Preview

Look at figure 1 of the pdf article you attached.

a) The metal is deposited on the substrate from two sources - effusion cells and electron beam evaporator. The rate at which this deposition takes place is the metal arrival rate on the substrate.

b) This will be the rate limiting step if the environment is oxygen-rich. There are two processes taking place i.e. 2 steps. One is the metal deposition on the substrate and the other is the reaction between the metal and oxygen. An oxygen-rich ...

Solution Summary

The rate limiting steps in metal oxide epitaxy is examined. What is meant by metal arrival rates being "rate limiting steps" is examined.