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Re: effective masses in silicon



Daniel,

The book "Energy Bands in Semiconductors", by Donald Long (Interscience
Publishers, 1968) lists experimental values of 0.96 and 0.19. Its
possible that more recent experiments have found slightly different
values. However, I would be suspicious of a value as large as 1.06.
Normally, effective masses near band minima or maxima in semiconductors
are smaller than the bare electron mass, not larger.

Hope this helps.

Charley Myles

__________________________________________________________________________

Charles W. Myles, Ph.D. Phone: (806) 742-3768
Professor Department Phone: (806) 742-3767
Department of Physics Department FAX: (806) 742-1182
Mail Stop 1051 Email: cmyles@gordian.phys.ttu.edu
Texas Tech University or t9cwm@ttacs.ttu.edu
Lubbock, Texas 79409-1051 Department Homepage: www.phys.ttu.edu
Texas Tech Homepage: www.texastech.edu




On Mon, 17 May 1999, Daniel Schroeder wrote:

Is there a semiconductor expert out there? I'm wondering what numbers
to use for the density-of-states effective masses of electrons and
holes in silicon. Kittel and Kroemer (chapter 13) give 1.06 and 0.58
times the bare electron mass for electrons and holes, respectively.
But my local solid-state physicist says 1.06 is way too high, referring
me to the book by Sze, which says the d-of-s effective mass is the
geometric mean of the effective masses in the three directions,
which it gives as .98, .19, and .19, respectively. The geometric
mean would then be only .33. (For holes there's hardly any
discrepancy.) Can anyone tell me why there might be such a
discrepancy, and which number I should use, say, in computing the
chemical potential of pure silicon at room temperature?

With many thanks,

Dan Schroeder
Weber State University
dschroeder@cc.weber.edu