Dynamic minority-carrier storage in TRAPATT diodes

The occurrence of a dynamic storage of minority carriers in the highly-doped boundary regions of a TRAPATT diode and the subsequent release of these carriers into the diode's depletion region is verified for the first time in detailed computer simulations of the diode's internal dynamics. The simulations were carried out by numerical solution of the carrier transport equations in a p⁺- n- n⁺ silicon diode having a deep-diffused doping profile typical of experimental devices. The results show that it is this storage process, and not thermal generation, that controls the carrier avalanche even in very gradually graded structures. The dynamics of this phenomenon are described in detail and the implications of the results on TRAPATT oscillator performance are discussed.