Microwave Faraday Effect in Silicon and Germanium

Abstract

The Faraday rotation and ellipticity in a system of quasifree carriers is discussed and applied to microwave measurements on semiconductors. The theoretical expressions for these effects are analyzed with a digital computer for various ranges of the magnetic field $B$, the mobility $\mu$, the conductivity $\sigma$, the frequency $\omega$, the collision time $\tau$ and the dielectric constant of the host material. It is possible to simplify these expressions in certain limiting cases. For $\mu B$ smaller than unity, the rotation and ellipticity are proportional to $B$. For $\mu B$ larger than both unity and $\omega \tau$, they decrease as $B^{-1\mathrm{}}$, and $B^{-3\mathrm{}}$, respectively. A maximum occurs near $\mu B=1\mathrm{}$ when $\omega \tau$ is small.