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Wednesday, April 22, 2015

Exploring Quantum Physics - Week 3 Extra Credit Question 8

Question: 

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What is the value of T for an electron in GaAs?

Solution:

It is a value hunting exercise. By one paper, we found out L=175. An is a Angstrom, which is basically 1010 meters.

On the effective mass of an electron in GaAs, another paper tell us the answer is 0.067m0, but what is m0? Turn out m0 is the electron mass and we can find it in the NIST values ,which is 9.10938291×1031 kg

To compute T, we will also need the Planck's constant, from the NIST website, it is 6.62606957×1034 J s.

So we compute T=8mL2h=2.2567×1013 s.
The last piece of the puzzle is a femtosecond, a femtosecond is basically 1015 second, so the final answer is 225.67 femtoseconds.

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