Electron-Hole Droplet Formation in Direct-Gap Semiconductors Observed by Mid-Infrared Pump-Probe Spectroscopy
Mid-infrared pump-probe measurements with subpicosecond time resolution reveal the existence of a metastable condensed phase of the electron-hole ensemble in a direct-gap semiconductor CuCl. High-density electrons and holes are directly created in a low-temperature state by the resonant femtosecond excitation of excitons above the Mott transition density. Strong metallic reflection with a plasma frequency {Dirac_h}{omega}{sub p}{approximately}0.5 eV builds up within 0.3 ps. Within a few picoseconds, the mid-infrared reflection spectrum is transformed from metalliclike into colloidlike. The observed resonance feature at {Dirac_h}{omega}{sub p}/{radical}3 allows us to obtain the carrier density in the metastable electron-hole droplets of 2{times}10{sup 20} cm{sup {minus}3} .
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40204692
- Journal Information:
- Physical Review Letters, Vol. 86, Issue 25; Other Information: DOI: 10.1103/PhysRevLett.86.5795; Othernumber: PRLTAO000086000025005795000001; 006125PRL; PBD: 18 Jun 2001; ISSN 0031-9007
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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