RESONANCE TUNNELING VIA EXCITED SUBBANDS AND THE EXISTENCE OF A NEW-TYPE OF ELECTRIC-FIELD DOMAINS IN LONG-PERIOD SUPERLATTICES

Successive resonance tunneling via excited states, accompanied by the appearance of resonance features on the multistability current-voltage branches, is observed in a superlattice. The data show a strongly non equilibrium charge-carrier distribution over subbands with energies be low the energy of an optical phonon and indicate that a new type of an electric-field domain forms, the structure of which is determined by resonance tunneling between excited subbands in neighboring quantum we lls. (C) 1997 American Institute of Physics.