Temperature Behavior of Gunn Oscillations in Planar InGaAs Diodes

Planar Gunn diodes on In _0.53 Ga _0.47 As with lengths between 2 and 5 μm have been fabricated and characterized in a temperature range of 10 to 300 K. Two different oscillation regimes are observed depending on temperature. At the higher values, the frequency of the oscillations decreases as the bias increases, as expected for a well-established transit-time domain mode. But below approximately 75 K, the behavior is the opposite, the frequency of the Gunn oscillations increases with the bias. This fact, together with a much lower amplitude of the oscillations, indicate the possible switch to a different oscillation mode in which the domains are not able to attain their complete maturation before reaching the anode.