About Physics 156

My office is ISB 243. Office hours are Monday and Friday 3:20-4:20 PM (or later if people are still around.)
email: The best way to contact me is by email at:
zacksc at gmail.com    (Please use this email and not any other emails you may have for me.)

Our final, assuming I am reading the UCSC schedule correctly, is on Wednesday, June 10 from noon to 3 PM.  That is scheduled by UCSC and set in stone. Other things are not completely certain at this time, but I expect that we'll have a midterm close to the middle of the quarter.

Our midterm will take one full class. I am thinking that May 11 would be a good date for that.

Quizzes: There may be online or in-class quizzes

Homework will be due mostly on Monday and Wednesday. Expect a lot of homework. Please keep all your returned HW in a homework portfolio to be turned in at the final.

This Blog will play a key role in the class. Please check it frequently and please participate in the discussions here. This is the place to ask questions.

Book: No book is required but Streetman (Solid State Electronic Devices, any edition) is probably pretty good. There are many similar books.  Pierret (Semiconductor Device Fundamentals) is also pretty good I think.

We will start with and examination of energy bands in crystals. A crystal is a system made of atoms in a perfect periodic arrangement. Energy bands are the bands of eigenvalues of crystal energy eigenstates (wave-functions) that arise when we solve the problem of a single electron in a spatially periodic potential. Crystals can be either semiconductors (Si, GaAs) or metals (Au, Fe, Pb). (An intrinsic semiconductor is essentially an insulator with a small energy gap.) Bands are the natural starting point to understanding semiconductors and semiconductor devices, as well as metallic behavior, magnetism, superconductivity and pretty much anything else that is based on the quantum behavior of electrons in a periodic potential.

So my plan is to start with bands. (The approach we are taking is called "tight-binding" (bad name) or, more descriptively, linear combination of atomic orbitals (LCAO). Reading about "free electron bands" may confuse you; that is a different approach that is not helpful for us and less reflective of the nature of anything real.) Then after "bands" I am thinking that we will transition quickly to understanding doped semi-conductors and then some semi-conductor devices such as p-n junctions and FETs (MOSFET for one).

Outline:
1. Review of quantum physics.
--wave functions and energies
    i) bound states. atoms. understanding the theoretical basis for the periodic table.
    ii) propagating (free particle) states. wave-packets.

2.Crystal quantum physics  
-----Constructing crystal wave functions from atomic wave functions. (Bloch states)
-----Crystal wave functions and their energies. Bands.

3. Bands and density of states. 
----What is a band? E vs k. How density of states is related to E vs k.
----The difference between a metal and a semiconductor.
----Valence and conduction bands.  What is an energy gap?
----Fermi function and DOS. How to use them together.
----Effective mass. Dispersion (E vs k) in 3D.

4. Doped semiconductors. Understanding \(E_f\) (also known as the chemical potential).

5. Conductivity:
  a) scattering rate
  b) effective mass

5. Understanding n-p junctions. What happens when you put dissimilar semiconductors together? How is equilibrium reached? etc. (This is the natural starting point for semiconductor device physics.)

6. a) Current flow in n-p junctions. Non-equilibrium thermodynamics. (This is not easy.)
b) Light emitting diodes and lasers.
c) solar cells.

7. Physics of Metals
a) Fermi surface
a) conductivity
b) color

8. Basic physics of superconductors
a) pairing
b) phase coherence
c) superfluidity

9. Magnetism
a) Pauli exclusion principle and electron-electron interaction.
b) why spins align (Ferromagnetism)

Here are some other things we might want to fit in somewhere:
The structure of silicon.
The structure of graphene.
The bands of graphene.
MOSFETS
Quantum computing. What other topics are you interested in? Please post here.