Accession Number : ADP007883

Title :   Tunneling and Relaxation in Coupled Quantum Wells,

Corporate Author : WEIZMANN INST OF SCIENCE REHOVOT (ISRAEL)

Personal Author(s) : Deveaud, B. ; Chomette, A. ; Clerot, F. ; Regreny, A. ; Gurvitz, S.

Report Date : 22 MAY 1992

Pagination or Media Count : 4

Abstract : In a double barrier resonant tunnelling diode, the lifetime of the electrons in the well is governed by the coupling of the confined states to the continuum of states outside the -barriers. The well states are broadened by the interaction with the continuum on each side of the structure and are thus metastable, even without any relaxation mechanism such as phonon emission. If an electron is injected into the structure as in the experiment of Tsuchyia, it will leak out with a time constant given only by the barrier thickness. In a system of coupled quantum wells (CQW) on the contrary, we are dealing with eigenstates of the system. Even at resonance, when one level of the narrow well (NW) is at the energy of a level of the wide well (WW), finite lifetimes are only observed because of additional perturbations to the system. In the absence of such perturbations, electrons would stay forever on the coupled levels (we are dealing here with a system prepared in a 'classical mixture' i.e. with electrons equally distributed in the two wells). The strongest perturbation, in the case where the coupled levels are separated from the ground state by more than one optical phonon, is the coupling to LO phonons.

Descriptors :   *TUNNELING(ELECTRONICS), *SEMICONDUCTOR DIODES, BARRIERS, CONSTANTS, COUPLINGS, ELECTRONS, EMISSION, ENERGY, GROUND STATE, INTERACTIONS, PERTURBATIONS, PHONONS, RELAXATION, RESONANCE, STRUCTURES, THICKNESS, FRANCE, QUANTUM ELECTRONICS.

Subject Categories : Solid State Physics
      Quantum Theory and Relativity

Distribution Statement : APPROVED FOR PUBLIC RELEASE