Tunneling and Relaxation in Coupled Quantum Wells,
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 22, 1992
- Accession Number
- ADP007883
Entities
People
- A. Chomette
- A. Regreny
- B. Deveaud
- F. Clerot
- S. Gurvitz
Organizations
- Weizmann Institute of Science