Optics of semiconductors with a linear electron spectrum
The temperature and carrier concentration dependences of the frequency dispersion of the dielectric constant of graphene and 3D semiconductors with a narrow band gap are examined at frequencies above the carrier relaxation frequency but well below the conduction band width. The linearity of the electronic spectrum over a wide range of energies, which is a general features of these materials, leads to an anomalously high dielectric constant of the 3D semiconductors, and when they are doped, to a logarithmic singularity in the real part of the dielectric function at the absorption threshold. For graphene, the optical transmission is determined by the fine structure constant of quantum electrodynamics, and is independent of any properties of graphene, itself.
Low Temperature Physics
- Pub Date:
- June 2011