Pressure Dependence of the Resistivity of Germanium

The effect of hydrostatic pressure on the resistivity of a sample of 35 ohm-cm germanium has been investigated up to 30 000 kg/${\mathrm{cm}}^2$ pressure at temperatures between 25°C and 76°C, and up to 7000 kg/${\mathrm{cm}}^2$ pressure at temperatures down to -195°C. The results indicate an increase in the total energy gap to 15 000 kg/${\mathrm{cm}}^2$ at a rate in agreement with earlier experimental determinations at lower pressures. A rapid rise in resistivity above 15 000 kg/${\mathrm{cm}}^2$ that seems to apply to $n$-type germanium crystals of any purity has also been investigated. Explanations based on the deionization of impurities and on a decrease in electron mobility are discussed.