Efficiency enhancement in avalanche diodes by depletion-region-width modulation

Gallium-arsenide avalanche-diode oscillators generally have direct operating voltages considerably lower than the punchtion in the depletion-region width during the r.f. cycle. This is in contrast to silicon devices, where it is ound that most structures are punched through¿or very nearly so¿at the operating voltage. In the letter, we consider the effect on the induced terminal current waveform of the time-varying depletion-region width. It is shown that, in diodes having a sufficiently under-punched-through structure and a high enough voltage modulation, the effect of this variation is to improve the current waveform and to increase the efficiency above that predicted by the Read sharp-pulse approximation. The theory has been found to give good agreement with published results for high-efficiency gallium-arsenide devices.