Microwave current oscillations have been observed in uniaxially compressednhyphen;type germanium in high electric field. For the configuration where the current is along the 112macr; crystal axis, and the strain along the 111 direction, the effect is present at 27deg;, 77deg;, and 300deg;K. At 27deg;K, the oscillations begin at stress of 1500 kgsol;cm2; the threshold electric field has a minimum of 270 Vsol;cm at a stress of 5000 kgsol;cm2. These values are higher at higher temperatures. The phenomenon is believed to be due to the existence of a region of bulk negative differential conductivity which results from intervalley transfer of electrons between the stresshyphen;split lang;111rang; valleys of the conduction band.
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