EFFECT OF NONUNIFORM CONDUCTIVITY ON BEHAVIOR OF GUNN EFFECT SAMPLES

The behavior of n+-n-n+ GaAs samples biased at voltages below the threshold for the onset of Gunn effect is derived. In particular, the spatial distribution of the electric field and the electron temperature, along with the current-voltage characteristics of the sample, are calculated. The specific structure considered has a low conductivity region in the n layer near one of the n+ contacts. This occurs for an alloyed contact made to an epitaxial layer of n-type GaAs grown on an n+ GaAs substrate. The most striking result is the occurrence of Gunn oscillations for one direction of bias and avalanche breakdown for the other. This and other experimental findings are consistent with the theory. © 1968 The American Institute of Physics.