Accession Number : ADP007821

Title :   Luminescence Anomaly of Two-Dimensional Excitons in GaAs Coupled Quantum Wells,

Corporate Author : IBM RESEARCH TOKYO (JAPAN) TOKYO RESEARCH LAB

Personal Author(s) : Fukuzawa, T.

Report Date : 22 MAY 1992

Pagination or Media Count : 3

Abstract : The possibility of a phase transition into an ordered state in a two-dimensional (2D) system of spatially separated electron-hole pairs has been suggested by Lozovik and Yudson and Shevchenko independently. Their proposal has recently been extended by Fukuzawa to a system formed by two GaAs/AlGaAs coupled quantum wells subject to an electric field. The long exciton lifetimes that can be achieved in such a semiconductor heterostructure, as well as the small Coulomb screening due to the interaction between oriented dipoles, make it particularly suitable for the study of phase transitions, be it like the one proposed by Lozovik and Yudson, and Shevchenko, or a Kosterliz-Thouless transition of a neutral Coulomb gas. The photoluminescence (PL) of GaAs-GaO.7A10.3As structures consisting of two 50A quantum wells separated by a 40A barrier has shown a dramatic temperature dependence when an electric field is applied perpendicular to the well interfaces. The polarization of carriers and the energy shifts induced by the field lead to a PL spectrum consisting of two distinct peaks, one of which is associated with spatially direct interband transitions and another, much more intense, that involves spatially-separated electrons and holes (type-11 exciton).

Descriptors :   *EXCITONS, *PHOTOLUMINESCENCE, *QUANTUM ELECTRONICS, BARRIERS, DIPOLES, ELECTRIC FIELDS, ELECTRONS, ENERGY, INTERACTIONS, INTERFACES, NEUTRAL, PHASE TRANSFORMATIONS, POLARIZATION, SEMICONDUCTORS, STRUCTURES, TEMPERATURE, GALLIUM ARSENIDES, ALUMINUM GALLIUM ARSENIDES, HETEROJUNCTIONS, CHARGE TRANSFER, JAPAN.

Subject Categories : Electrooptical and Optoelectronic Devices

Distribution Statement : APPROVED FOR PUBLIC RELEASE