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Band Dispersion and Career Mobility

by arvind
Tags: band, career, dispersion, mobility
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arvind
#1
Jun29-14, 01:40 AM
P: 2
how the dispersion relation(i.e. E-k relation) affects carrier mobility in metals or semi-metals?
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ZapperZ
#2
Jun29-14, 09:46 AM
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Quote Quote by arvind View Post
how the dispersion relation(i.e. E-k relation) affects carrier mobility in metals or semi-metals?
I'm not sure if you have done any search on your own. You would have discovered the answer yourself.

For example, the electron mobility can be written, in the simplest form, as

[tex]\mu = e\tau/m^*[/tex]

where μ is the mobility, τ is the scattering time, e is the charge, and m* is the effective mass. Now, look up the relationship between the effective mass and the band dispersion, and you have your answer.

Zz.
arvind
#3
Jul1-14, 08:56 PM
P: 2
what if the charge carriers are massless as in case of graphene which is a single atom thick sheet?

DrDu
#4
Jul2-14, 02:35 AM
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Band Dispersion and Career Mobility

Quote Quote by arvind View Post
what if the charge carriers are massless as in case of graphene which is a single atom thick sheet?
In general, the velocity of a wavepacket describing the motion of a particle is given as ##\partial E/\partial k##. You can now figure out what happens for a quadratic and a linear dispersion relation.
The book by Ashcroft and Mermin discusses all this in detail.
Douasing
#5
Sep17-14, 04:56 AM
P: 35
Quote Quote by ZapperZ View Post
I'm not sure if you have done any search on your own. You would have discovered the answer yourself.

For example, the electron mobility can be written, in the simplest form, as

[tex]\mu = e\tau/m^*[/tex]

where μ is the mobility, τ is the scattering time, e is the charge, and m* is the effective mass. Now, look up the relationship between the effective mass and the band dispersion, and you have your answer.

Zz.
Is there a simple and convenient way to estimate the electron mobility ?
I can derive the [itex]m^*[/itex] from band structure data ( through curve-fitting and then take a derivative with respect to k-point),but I know little information for the scattering time ;how to estimate [itex]\tau[/itex] for the systems (for example, BN sheet,or phosphorus) ?
There is also another formula ,i.e.,
[tex]\upsilon_{d}=μE[/tex]
it seems not cowork with those data using first princple softwares.
DrDu
#6
Sep17-14, 11:40 AM
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Quote Quote by Douasing View Post
Is there a simple and convenient way to estimate the electron mobility ?
Not really, it depends on the scattering mechanism, e.g. impurity scattering or scattering from phonons. The latter should be most relevant in very pure samples. To quantify it ab initio, you would have to calculate the phonon spectrum and electron phonon coupling constants.


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