Current Oscillations in n-Type Ge at Low Temperatures

Measurements were performed in high-purity n-type germanium in the temperature range 15–30 K with the electric field applied in the [111], [110], and [100] directions. A large anisotropy of the conductivity was observed. In the case of the [111] orientation, current oscillations in the megahertz range were observed in the electric field range 3–20 V/cm. The results are consistent with the theory of electron transfer among 〈111〉 valleys of the conduction band in germanium.