Results from capacitance measurements on $n$-type silicon versus donor concentration show the onset of a possible divergence (polarization catastrophe) in the static dielectric constant at a critical concentration $N_c$, which is donor dependent, as $N_c$ is approached from the insulating side. A substantial deviation from Clausius-Mosotti behavior occurs as $N\to N_c$.

• Received 30 April 1975

DOI:https://doi.org/10.1103/PhysRevLett.34.1627