|
Diploid
Cuban


Registered: 01/09/03
Posts: 19,274
Loc: Rabbit Hole
|
Electron Band Structure In Germanium, My Ass
#5666435 - 05/23/06 08:48 PM (17 years, 8 months ago) |
|
|
http://www.cs.wisc.edu/~kovar/hall.html
Electron Band Structure In Germanium, My Ass
Abstract: The exponential dependence of resistivity on temperature in germanium is found to be a great big lie. My careful theoretical modeling and painstaking experimentation reveal 1) that my equipment is crap, as are all the available texts on the subject and 2) that this whole exercise was a complete waste of my time.
Introduction
Electrons in germanium are confined to well-defined energy bands that are separated by "forbidden regions" of zero charge-carrier density. You can read about it yourself if you want to, although I don't recommend it. You'll have to wade through an obtuse, convoluted discussion about considering an arbitrary number of non-coupled harmonic-oscillator potentials and taking limits and so on. The upshot is that if you heat up a sample of germanium, electrons will jump from a non-conductive energy band to a conductive one, thereby creating a measurable change in resistivity. This relation between temperature and resistivity can be shown to be exponential in certain temperature regimes by waving your hands and chanting "to first order".
Experiment procedure
I sifted through the box of germanium crystals and chose the one that appeared to be the least cracked. Then I soldered wires onto the crystal in the spots shown in figure 2b of Lab Handout 32. Do you have any idea how hard it is to solder wires to germanium? I'll tell you: real goddamn hard. The solder simply won't stick, and you can forget about getting any of the grad students in the solid state labs to help you out.
Once the wires were in place, I attached them as appropriate to the second-rate equipment I scavenged from the back of the lab, none of which worked properly. I soon wised up and swiped replacements from the well-stocked research labs. This is how they treat undergrads around here: they give you broken tools and then don't understand why you don't get any results. Fig. 1: Check this shit out. In order to control the temperature of the germanium, I attached the crystal to a copper rod, the upper end of which was attached to a heating coil and the lower end of which was dipped in a thermos of liquid nitrogen. Midway through the project, the thermos began leaking. That's right: I pay a cool ten grand a quarter to come here, and yet they can't spare the five bucks to ensure that I have a working thermos.
Results
Check this shit out (Fig. 1). That's bonafide, 100%-real data, my friends. I took it myself over the course of two weeks. And this was not a leisurely two weeks, either; I busted my ass day and night in order to provide you with nothing but the best data possible. Now, let's look a bit more closely at this data, remembering that it is absolutely first-rate. Do you see the exponential dependence? I sure don't. I see a bunch of crap. Christ, this was such a waste of my time.
Banking on my hopes that whoever grades this will just look at the pictures, I drew an exponential through my noise. I believe the apparent legitimacy is enhanced by the fact that I used a complicated computer program to make the fit. I understand this is the same process by which the top quark was discovered.
Conclusion
Going into physics was the biggest mistake of my life. I should've declared CS. I still wouldn't have any women, but at least I'd be rolling in cash.
-------------------- Republican Values: 1) You can't get married to your spouse who is the same sex as you. 2) You can't have an abortion no matter how much you don't want a child. 3) You can't have a certain plant in your possession or you'll get locked up with a rapist and a murderer. 4) We need a smaller, less-intrusive government.
Edited by Diploid (05/23/06 08:56 PM)
|
HagbardCeline
Student-Teacher-Student-Teacher


Registered: 05/10/03
Posts: 10,026
Loc: Overjoyed, at the bottom ...
Last seen: 19 days, 3 hours
|
Re: Electron Band Structure In Germanium, My Ass [Re: Diploid]
#5666845 - 05/23/06 10:47 PM (17 years, 8 months ago) |
|
|
A+
-------------------- I keep it real because I think it is important that a highly esteemed individual such as myself keep it real lest they experience the dreaded spontaneous non-existance of no longer keeping it real. - Hagbard Celine
|
trendal
J♠


Registered: 04/17/01
Posts: 20,815
Loc: Ontario, Canada
|
Re: Electron Band Structure In Germanium, My Ass [Re: Diploid]
#5669395 - 05/24/06 04:48 PM (17 years, 8 months ago) |
|
|

"I should've declared CS. I still wouldn't have any women, but at least I'd be rolling in cash."
--------------------
Once, men turned their thinking over to machines in the hope that this would set them free. But that only permitted other men with machines to enslave them.
|
debianlinux
Myconerd - DBK



Registered: 12/09/02
Posts: 8,334
Loc: Over There
Last seen: 7 months, 1 day
|
Re: Electron Band Structure In Germanium, My Ass [Re: Diploid]
#5669581 - 05/24/06 05:56 PM (17 years, 8 months ago) |
|
|
I say you have cold joints on your crystal. Try resoldering them.
j/k
|
RiverMan
experiencednewbie

Registered: 06/26/04
Posts: 105
Last seen: 15 years, 20 days
|
Re: Electron Band Structure In Germanium, My Ass [Re: Diploid]
#5670106 - 05/24/06 08:09 PM (17 years, 8 months ago) |
|
|
That's a nice exponential function you got there
|
Baby_Hitler
Errorist



Registered: 03/06/02
Posts: 27,587
Loc: To the limit!
Last seen: 7 hours, 5 minutes
|
Re: Electron Band Structure In Germanium, My Ass [Re: Diploid]
#5671814 - 05/25/06 07:52 AM (17 years, 8 months ago) |
|
|
I'd ask you if you go to the same ghetto University I do, but my tuition is only $2000 a semester and the government is paying for that.
We have brand new $10,000 digital projectors in every classroom, but the breadboards are all corroded and busted and most of the teachers can't speak the english so well.
-------------------- Ƹ̵̡Ӝ̵̨̄Ʒ Ƹ̵̡Ӝ̵̨̄Ʒ Ƹ̵̡Ӝ̵̨̄Ʒ Ƹ̵̡Ӝ̵̨̄Ʒ Ƹ̵̡Ӝ̵̨̄Ʒ Ƹ̵̡Ӝ̵̨̄Ʒ Ƹ̵̡Ӝ̵̨̄Ʒ Ƹ̵̡Ӝ̵̨̄Ʒ Ƹ̵̡Ӝ̵̨̄Ʒ Ƹ̵̡Ӝ̵̨̄Ʒ Ƹ̵̡Ӝ̵̨̄Ʒ Ƹ̵̡Ӝ̵̨̄Ʒ Ƹ̵̡Ӝ̵̨̄Ʒ Ƹ̵̡Ӝ̵̨̄Ʒ Ƹ̵̡Ӝ̵̨̄Ʒ Ƹ̵̡Ӝ̵̨̄Ʒ (•_•) <) )~ ANTIFA / \ \(•_•) ( (> SUPER / \ (•_•) <) )> SOLDIERS / \
|
|