where from I see it I believe that dielectric constant should increase with an increase in bandgap but reports and wiki show an indirect relation if it is so then why do insulators have high dielectric constant obviously bandgap has a part to play. It is the bandgap that gives rise to the dielectric/insulating properties of the material then why is it so that reports suggest an indirect relation. Plz need answers if any....
Dear Feroz A. Najar ,
The factor affecting the energy gap is the dielectric constant, which depends on the density of atoms and their polarizability. The dielectric constant is proportional to N the density of atoms per cm^3 and the alpha the polarizability. The polarizability depends on the electronic structure of the atom. It is so that the energy gap is inversely proportional to the dielectric constant which in turn is inversely proportional to the inter-atomic distance.
Now, coming to your query regarding insulators, yes they have high dielectric constants, but here you should recall what exactly dielectric constant physically signify, it states how polarizable atoms in a material are under the influence of an electric field. There are instance wherein materials have dielectric constant and high conductivity.
Regards,
KP
Dear Feroz A Najar ;
In general, the dielectric constant is inversely proportional to the square of the band gap energy. Therefore, a higher dielectric constant would have a smaller band gap energy. but each case has a different condition according to the related affecting morphological parameters., as detailed in the following references;
- https://www.mdpi.com/2073-4360/12/8/1714/htm
- Ravichandran, R.; Wang, A.X.; Wager, J.F. Solid State Dielectric Screening versus Band Gap Trends and Implications. Opt. Mater. 2016, 60, 181–187.
- Hervé, P.; Vandamme, L.K.J. General Relation between Refractive Index and Energy Gap in Semiconductors. Infrared Phys. Technol. 1994, 35, 609–615.
- file:///C:/Users/POWERLOGIC/Desktop/srep5201516939.pdf
I agree my colleagues KP and FAN and I think that you have found some clarification.
Hello,
I think it's inversely related, however, there is interdependence among the inter-atomic distance, size, and shape of the nanocrystals.
Thank you!
Dear Feroz A Najar,
The energy gap is inversely proportional to the dielectric constant which in turn is inversely proportional to the inter-atomic distance.
Best of Luck.
Lee, Miso, Yong Youn, Kanghoon Yim, and Seungwu Han. "High-throughput ab initio calculations on dielectric constant and band gap of non-oxide dielectrics." Scientific reports 8, no. 1 (2018): 1-8.
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