Re: [Phys-l] solid state physics

["Diff, Karim" <karim.diff@sfcc.edu>]

The effective mass is actually a tensor with different values depending 
on the direction within the Brillouin zone. The relationship between 
energy and wave number
( E = hbar^2 * k^2/2m* ) is valid only near a minimum in the conduction 
band ( usually the Gamma point where k = 0, but in the case of silicon  
that is near the X point of symmetry)
where the energy is a parabolic ( a function of k^2) but gets quite 
complicated further away. In the case of silicon the longitudinal 
effective mass is 0.98*m0 and the transverse effective mass is 0.19*m0 
where m0 is the free electron mass.

Some online references:

<http://www.ee.ui.ac.id/~astha/courses/ts/teksem/effmass.htm>

<http://www.wsi.tu-muenchen.de/nextnano3/input_parser/database/docu/effective_masses.htm>

<http://mems.caltech.edu/courses/EE40%20Web%20Files/effective%20mass%20explanation.pdf>

<http://tinyurl.com/s97d7>


Karim Diff



Stefan Jeglinski wrote:

> > For details see a book on solid-state physics e.g. Ashcroft & Mermin.
> > I tried googling but did not immediately find any cogent discussions
> > online.  I can find the diagram:
> >   http://www.uvm.edu/~dcloughe/images/si.gif
> > and others via
> >   http://images.google.com/images?q=silicon+band-structure
> > but not much useful discussion.
> >    
>
> LOL, speak for yourself. I refer to a site found by clicking your 
> google images link:
>
> http://britneyspears.ac/physics/basics/basics.htm
>
> The discussion halfway down the page, on band structure and effective 
> mass, includes the illuminating band diagram :-)
>
> True, I did not find the answer to the immediate question at hand. 
> Seriously, I will search through my SS texts to see if I can add 
> anything more that's actually worth something.
>
>
>
> Stefan Jeglinski
>
>
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