COHERENT ELECTRON-HOLE BCS STATE: STUDY OF DYNAMICS
Vasil'ev P.P., Kan H., Ohta H., Hiruma T.

Received: July 26, 2002

PACS: 71.35.Lk, 42.50.Fx

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The first experimental study of the evolution of a coherent electron-hole (e-h) BCS-like state in bulk GaAs at room temperature is presented. We demonstrate explicitly that the total spontaneous emission from e-h pairs located within the conduction and valence bands approaches zero when the radiative recombination of the e-h BCS state occurs. This confirms that a vast majority of electrons and holes available is condensed at the very bottoms of the bands and forms the BCS state. An average lifetime of this state is measured to be around 300 fs. We also show that the coherence of electrons and holes of the BCS state preserves for a much longer time compared to the intraband relaxation time T₂.