Dear Abdulghefar,

The relationship between the dielectric constant epsilon and the refractive index n is the same irrespective of the material type, provided that the relative permeability is nearly one which is valid for nonmagnetic material. Formally, this relation is expressed by n= square root of epsilon .Because of dielectric losses, both quantities are complex where the complex dielectric constant with real and imaginary parts \ \epsilon_1 and \ \epsilon_2, and n and \ \kappa are the real and imaginary parts of the refractive index, all functions of frequency:

epsilon= epsilon_1+ i epsilon_2= (n+i kappa)^2.

Now we come to the major differences:

The semiconductor has relatively much higher conductivity sigma than the dielectric material depending on the doping concentration of the semiconductor material. Wide band gap intrinsic semiconductors approache the insulator behavior. So, any disc of the material with area A and thickness t , will have a capacitance C in addition to a coductance G where C= epsilon0 epsilon A/t and G= Sigma A/t.

It is clear that in addition to the dielectric polarization losses, there will be coductive ohmic losses.This must be taken into consideration when we measure dielectric losses in order to determine the imajnary part of the dielectric const or Kappa of the refractive index. One has to subtract the conductive losses from the overall losses to determine the dielectric polarization losses. One may overcome the ohmic losses in semicoductors by making the measurements on the depleted regions of pn junctions.Such regions behave as insulator.

The second and last difference is in the in the frequency behavior of the polarisation in the two class of materials.Semiconductors have predominantly electronic polarization because of their covalent bonds. The insulator may have permanent dipole polarization,ionic polarization and electronic polarization affecting much their real and imaginary parts of the dielectric constant and the refractive index.

I hope i could shed some light on this important topic.

Wish you success Abdulghefar.

Dear Abdulghefar,

The relationship between the dielectric constant epsilon and the refractive index n is the same irrespective of the material type, provided that the relative permeability is nearly one which is valid for nonmagnetic material. Formally, this relation is expressed by n= square root of epsilon .Because of dielectric losses, both quantities are complex where the complex dielectric constant with real and imaginary parts \ \epsilon_1 and \ \epsilon_2, and n and \ \kappa are the real and imaginary parts of the refractive index, all functions of frequency:

epsilon= epsilon_1+ i epsilon_2= (n+i kappa)^2.

Now we come to the major differences:

The semiconductor has relatively much higher conductivity sigma than the dielectric material depending on the doping concentration of the semiconductor material. Wide band gap intrinsic semiconductors approache the insulator behavior. So, any disc of the material with area A and thickness t , will have a capacitance C in addition to a coductance G where C= epsilon0 epsilon A/t and G= Sigma A/t.

It is clear that in addition to the dielectric polarization losses, there will be coductive ohmic losses.This must be taken into consideration when we measure dielectric losses in order to determine the imajnary part of the dielectric const or Kappa of the refractive index. One has to subtract the conductive losses from the overall losses to determine the dielectric polarization losses. One may overcome the ohmic losses in semicoductors by making the measurements on the depleted regions of pn junctions.Such regions behave as insulator.

The second and last difference is in the in the frequency behavior of the polarisation in the two class of materials.Semiconductors have predominantly electronic polarization because of their covalent bonds. The insulator may have permanent dipole polarization,ionic polarization and electronic polarization affecting much their real and imaginary parts of the dielectric constant and the refractive index.

I hope i could shed some light on this important topic.

Wish you success Abdulghefar.

certainly you did Dr, Zekry, thank you very much for your informative explanation.