Polarization Conductivity inp-Type Germanium

Abstract

The ac conductivity ${\sigma }_{\mathrm{ac}}$ of $p$-type Ge was measured over the frequency range of ${10}^2$ to ${10}^5$ cps and in the impurity conduction temperature range of 1.2 to 4.2°K. Doping by transmutation insured a constant donor to acceptor concentration ratio of 0.4. The acceptor concentration ranged from 3×${10}^{14}$ to 2×${10}^{15}$/cc. The observed frequency and concentration dependence of ${\sigma }_{\mathrm{pol}}={\sigma }_{\mathrm{ac}}-{\sigma }_{\mathrm{dc}}$ can be understood on the basis of the polarization model of Pollak and Geballe. The observed temperature dependence can be understood by considering the interaction between ionized donors and electrons. From the absolute magnitude of ${\sigma }_{\mathrm{pol}}$, the Bohr radius of the acceptor wave function is found to be about 74 Å, in good agreement with that found from dc measurements.