On the degradation of GaSb tunnel diodes

This paper reports on the modes of failure of GaSb tunnel diodes and a model which explains the major experimental observations. When GaSb tunnel diodes are biased at positive voltages well past the valley region, permanent changes in the tunnel diode characteristics occur. In this case both the peak and the valley currents go up with degradation. This is to be contrasted with GaAs tunnel diodes in which the peak current always goes down. When the GaSb tunnel diode is biased at a fixed voltage in the so-called "injection region," the peak and the valley currents increase exponentially with time with a well defined final value for each. The difference between the final and the initial values of the valley is larger than that of the peak. The peak current reaches its final value before the valley current. Under proper experimental circumstances it can be shown that the failure process not only continues after being initially biased in the "injection region" but is actually accelerated for a period of time by the removal of bias. The proposed model explains all the above observations and several others. It also explains how and why some reversible as well as irreversible changes are experimentally observed. Observed changes in capacitance with failure are consistent with the proposed model.