Double-barrier THz source based on electrical excitation of electrons and holes

A detailed dynamical analysis of an all solid-state THz source is given. Th is is based on the polarization-induced autonomous oscillation in resonant tunneling heterostructure with staggered band-gap alignment. The physical m odel consists of the following processes: (a) Generation by Zener tunneling of holes trapped in the barrier and electrons drifting in the depletion la yer of the drain, whose rate decreases with the polarization between the ba rrier and quantum well. (b) Stimulated generation of barrier-well polarizat ion. (c) Nonradiative decay of barrier-well polarization through barrier-ho le recombination and quantum-well electron discharge. It is shown that a li mit cycle oscillation of the barrier-well polarization and trapped-hole cha rge in the barrier can occur which induce THz oscillations in the resonant tunneling current across the device. The time-averaged results agree with t he measured current-voltage characteristic of AlGaSb/InAs/AlGaSb staggered band-gap double-barrier structure. In particular, the measured smaller curr ent offset at forward bias compared to that of reverse bias in the current- voltage hysteresis loop is predicted by our physical model and limit cycle analysis. Thus, we have experimental evidence indicating the correctness of our approach and the promising potential of this device as a novel all sol id-state THz source. (C) 1999 American Institute of Physics. [S0021-8979(99 )07221-7].