Hot Electrons in Indium Antimonide

Pulsed measurements of the Hall voltage in high-purity $n$-type InSb at 77°K allow calculation of the electron drift velocity as a function of the applied electric field. Drift velocities as large as 9×${10}^7$ cm/sec are observed. The behavior for moderate electric fields (below the threshold for electron-hole pair production) is in good agreement with a theory assuming scattering by polar optical modes. The large drift velocities indicate a large velocity-space anisotropy for the electrons, with a ratio of drift to "thermal" velocity as high as 1.5. It is suggested that an observed anomaly in the drift velocity behavior, i.e., a sharp drop in value at the highest electric fields, is related to possible generation of high-frequency oscillations through the mechanism of the two-stream instability.