### Author Topic: effective mass  (Read 1491 times)

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#### rupesh_shukla

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##### effective mass
« on: May 31, 2017, 08:10 »
i am calculating the effective mass from band structure... but how to define and differentiate between electron and hole effective mass ...because the effective mass calculation just shows effective mass ...it does not tell whether its for holes or for electrons..

#### Jess Wellendorff

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##### Re: effective mass
« Reply #1 on: May 31, 2017, 08:40 »
Please have a look at this tutorial: http://docs.quantumwise.com/tutorials/effective_mass/effective_mass.html
Derivatives of electronic conduction bands are in solid state physics connected to the electron effective mass, while for the valence bands (i.e. bands below the Fermi level) we call the particles holes instead of electrons.
The Effective Mass Analyzer tells you the band energy that the effective mass was obtained at (relative to the Fermi level). Positive band energies therefore means electrons, negative band energies mean holes.

#### rupesh_shukla

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##### Re: effective mass
« Reply #2 on: May 31, 2017, 15:33 »
some times during effective mass calculation ...result is in negative effective mass... what does it signify ??  positive band energies also  results in negative effective mass at times...

#### lknife

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##### Re: effective mass
« Reply #3 on: May 31, 2017, 16:54 »
The negative effective mass is all right. That mostly occurs at the conduction band minimum (CBM). That means the effective mass is for electrons. The positive effective mass occurs at the valance band maximu (VBM) and is for holes. You can refer to any books on solid state physics.

#### lknife

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##### Re: effective mass
« Reply #4 on: May 31, 2017, 16:56 »
The sign of the effective mass is just related to the curvature of the band.