Microwave oscillations in pnp reach-through BARITT diodes

Abstract Studies have been made on the microwave oscillations of reach-through p + np + and related structures operated as BARITT diodes (BARrier Injection Transit Time diodes). The mechanisms responsible for the microwave oscillatins are the exponential increase of the local carrier population at the forward-biased pn junction and the transit-time delay of injected carriers transversing the drift region. The small-signal impedance and noise measure of the device are calculated based on (1) the thermionic injection and the space-charge-limited effects and (2) the separation of the drift region into a low-field region and a saturated-velocity region. Microwave CW oscillatins have been obtained from p + np + BARITT diodes made from an epitaxial n on p + silicon substrate with epitaxial layer thickness of 8 μm and doping concentration of 5 × 10 14 cm −3 . Microwave CW power of the order of a few milliwatts has been obtained at 7 GHz with efficiency greater than 1 per cent. Good agreement has been obtained between the measured and the calculated small-signal impedances.