Time-resolved formation of excitons and electron-hole droplets in si studied using terahertz spectroscopy.

We investigated the formation dynamics of excitons and electron-hole (e-h) droplets (EHDs) in Si by using broadband terahertz time-domain spectroscopy. The formation of indirect excitons in Si was studied by observing their 1S-2P transition. Changes in surface plasmon resonance of the EHDs showed a gradual condensation from homogeneous e-h plasma at e-h densities above the exciton-Mott transition. Excitonic correlations were shown to exist prior to EHD condensation even above the Mott density.