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# Investigating Bandgap energies

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As a practical matter, GaAs and GaP are soluble in all proportions, and the band gap of the alloy increases nearly linearly with the molar additions of GaP. The band gap of pure GaP is 2.25 eV. Calculate the molar fraction of GaP required to produce the 1.78 eV band gap.

https://brainmass.com/physics/energy/investigating-bandgap-energies-348835

#### Solution Preview

The way I see it

Bandgap energy {E(b)} is linearly proportional to Molar concentration of GaP (M) in the GaAs,GaP alloy. Let us call this constant of proportionality {p}

Then we can ...

#### Solution Summary

Using data on the bandgap energies of pure GaAs and given information on linear relationship of bandgap energy with addition of GaP molar concentration the estimated molar concentration of GaP required to bring the concatentated bandgap of mixed GaAs doped with GaP to 1.78 eV is deduced

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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.

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