Experimental study of the control characteristics of a Schottky-trigger electrode on a Gunn device

To clarify the condition for the generation of a high-field domain in a Gunn device equipped with a Schottky-trigger electrode, a detailed experimental study was carried out. The difficulties in such experiments had so far rested in the accurate evaluation of the potential difference between the trigger electrode and the semiconductor thereunder, which we solved by an equivalent circuit representation of the device. Moreover, the accuracy of the evaluation of the potential difference was further increased by making use of the critical condition for the forward current through the Schottky barrier of the trigger electrode. From the experimental results it was made clear that a high-field domain is not necessarily generated when the field in the channel under the trigger electrode reaches the threshold field, but some form of the over-threshold-field state is established before a domain is generated. This shows that the device could be biased to higher anode voltages, leading to higher output voltages and wider operational margines than had earlier been expected.