Electron drift velocity in high-purity Ge between 8 and 240K

Electron drift velocity in high-purity crystalline Ge as a function of electric field (1-10 4 V cm -1 ) and temperature (8-240K) was measured using the time-of-flight technique, the electric field being applied parallel to the (100) crystallographic axis. The drift mobility in the ohmic region is in agreement with theoretical predictions. Negative differential mobility is found for temperatures below 130K and is enhanced by lowering the temperature further. At 8K a negative differential mobility of 600 cm 2 V -1 s -1 is observed with a threshold electric field of 1 kV cm -1 .