A comparison between N-type and P-type InP LHL IMPATT diodes

This paper presents a comparison between the performance of N- and P-type InP IMPATT diodes. This is important to deeply understand the operation of these devices. For the P-type diodes, it is found that the operation is always according to the conventional IMPATT mode. The depletion-layer-width modulation is the main factor responsible for the lower efficiency. This effect causes the induced current to undergo a dip at the worst time in the cycle and delays the extraction of the carriers. It is indicated that the velocity-field characteristic of N-type InP material is the main factor responsible for the high-efficiency operation of N-type IMPATTs. During this high-efficiency operation, the avalanche-generated packet of electrons is bunched and accelerated. It may also be prematurely collected. This causes the induced current to have one or two additional peaks at the proper phase angles in the RF cycle.