Effect of Domain and Circuit Properties on Oscillations in GaAs

A discussion is given of the complications obtaining when a bar of GaAs, generating microwave oscillations, is allowed to interact with an external circuit. Three very different modes of operation can be expected, each corresponding to a mechanism of extinction of the travelling domains of electric field that cause the current modulation. It is seen that the domains may be extinguished (1) when they reach the end of the bar, (2) when the voltage drops too low for the stability of a domain, or (3) when it rises too high. In the last two circumstances, the external circuit plays an important role. Conditions for the existence of the various modes are deduced, and their properties are studied experimentally.