At-a-Glance
MedeA®[5] Electronics computes key electronic properties of metals, semiconductors, and insulators including isoenergy (Fermi) surfaces, electronic contributions to the electrical and thermal conductivity, thermoelectric power, and effective masses.
Key Benefits
Due to the Pauli principle, only the electronic states at the Fermi energy, and within a narrow energy range of width kBT around it, govern a material’s response to external electric or magnetic fields, or temperature gradients. Thus insight into the energy distribution of these states, and the nature of their wave functions thus is of utmost importance for understanding the material’s properties.
MedeA Electronics explores the electronic states within a narrow energy range about the Fermi energy, by giving access to ground-state properties, such as Fermi surfaces, specific heats, and effective masses, as well as transport properties, like the electronic contributions to the electrical and thermal conductivities and the thermoelectric power.
For example, the Fermi surface of MoO2, as shown in the Figure below, identifies three different sheets, namely, an electron-like peanut-shaped Fermi surface centered at the \(\Gamma\) point and two smaller hole-like Fermi surfaces each, centered at the Y point, explaining the anisotropic electrical conductivity. Both angle-resolved photoemission spectroscopy and de Haas-van Alphen measurements show very good agreement with calculated Fermi surfaces, and thus underline the predictive power of first-principles calculations [6].
Calculated effective masses of silicon’s hole and electron states of given in the following table likewise agree almost perfectly with experimental data.
Exp. [3] | Exp. [4] | MedeA | |
---|---|---|---|
Electrons | |||
Long Eff. Mass | 0.98 | 0.98 | 0.96 |
Trans Eff. Mass | 0.19 | 0.19 | 0.19 |
DOS Mass | 1.08 | 1.08 | 1.08 |
Conductivity Mass | 0.26 | 0.26 | 0.26 |
Light Hole | |||
Eff. Mass | 0.16 | 0.16 | 0.18 |
Split-off Band | |||
Eff. Mass | 0.29 | 0.24 | 0.23 |
[3] | http://ecee.colorado.edu/~bart/book/effmass.htm` |
[4] | http://www.ioffe.rssi.ru/SVA/NSM/Semicond/Si/bandstr.html` |
In addition, the strong anisotropy of the \(\Gamma\)-point hole states is nicely demonstrated in the figure below, which illustrates the isosurface of the electronic states of Si at 0.7 eV below the valence band maximum.
Learn more about MedeA Electronics by checking out the following on Materials Design Application Notes page:
Check out the Datasheets on MedeA Fermi Surface and MedeA Electronic Transport for additional information.
[5] | MedeA and Materials Design are registered trademarks of Materials Design, Inc. |
[6] | J. Moosburger-Will, J. Kündel, M. Klemm, S. Horn, P. Hofmann, U. Schwingenschlögl, and V. Eyert, Phys. Rev. B 79, 115113 (2009) (DOI) |
[7] | R. Sehr and L. R. Testardi, J. Phys. Chem. Solids 23, 1219 (1962) (DOI) |
[8] | H. J. Goldsmid, “Thermoelectric Refrigeration”, (Springer, New York, 1964) (DOI) |
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