For homework due next Friday (Feb 27) please do the following:
(This covers two very different areas and types of problems, so I would suggest starting soon and expecting it to involve more time and effort than usual. Also, it may count up to 2x more than other HW's.)
1-3) The problems from the virtual quiz (see previous post).
4) Based on considerations similar to those you used in the above problems (from the quiz), discuss your thoughts on what the nature of gold (Au) might be. Include discussion of the total number of electrons per atom, how many might stay localized and how many, if any, go into non-localized states...
5) (Extra credit) Do the same for Ge (germanium). [Hint: For Ge, try assuming that there is a core which is like Ar (argon) but with exactly 10 extra electrons filling a "d-state mini-shell"
6) [Extra credit) If Ge is similar to Si, then speculate as to what a semiconductor which is exactly half Ga atoms and half As atoms (gallium and arsenic) would be like. Assume that they are in a perfectly ordered structure with each Ga having 4 nearest neighbors of As and visa versa. (Ask me to draw this in class if you like). How many electrons does each atom have, where do they go, etc? Is this similar to salt* or to Si or ...?
*NaCl
Also please do book problems: Chapter 23, Problems 2, 3, 4, 6, 7 and 8 , with 6 being extra credit.
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Ge:
ReplyDeleteBased on various experiments (phenomenology) we have a sense that Ge is similar to Si. To try to understand why that might be, we can start be looking at the periodic table. Just seeing that Ge is "under" Si is not enough. What does that mean? How many electrons does Ge have? How many more than the nearest noble gas core? (What is the nearest noble gas core?) For Ge, and to try to understand Au, you can assume a filled d-shell which takes up exactly 10 electrons. How many valence electrons does that leave to consider??
Ga is just to one side of Ge, i think, and As is on the other side. What could they do to enable them to bond in a structure just like Si and Ge?
Where could we look for any information about localized and non-localized electron. It would be best if it was more detailed since it was hard for me to grasp that concept.
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