Direct Measurement of the Dielectric Constants of Silicon and Germanium

Direct measurements of dielectric constants of silicon and germanium between 500 cps and 30 Mc/sec have been made. Small parallel-plate condensers were made from samples of these elements after doping with gold so as to produce high-resistivity material (ρ~10⁷ ohm cm for germanium at 77^∘{}K, >10¹⁰ ohm cm for silicon). The dielectric constant of silicon (at 1 Mc/sec) was taken to be 11.7±{}0.2, of germanium 15.8±{}0.2. The dielectric constant of silicon is constant to ±{}1 percent over the range 500 cps-30 Mc/sec, whereas germanium, because of its lower resistivity, has a much greater apparent variation of dielectric constant with frequency.