Exciton Mott transition in Si Revealed by Terahertz Spectroscopy

TL;DR

This study uses terahertz spectroscopy to investigate the exciton Mott transition in silicon, revealing persistent excitonic correlations and plasmon-exciton coupling near the Mott density.

Contribution

It provides experimental evidence of excitonic correlations above the Mott density and observes plasmon-exciton coupling in silicon.

Findings

Excitonic 1s-2p resonance persists above Mott density

Charge carrier scattering rate peaks near Mott density

Detection of plasmon-exciton coupling in loss spectra

Abstract

Exciton Mott transition in Si is investigated by using terahertz time-domain spectroscopy. The excitonic correlation as manifested by the 1s-2p resonance is observed above the Mott density. The scattering rate of charge carriers is prominently enhanced at the proximity of Mott density, which is attributed to the non-vanishing exciton correlation in the metallic electron-hole plasma. Concomitantly, the signature of plasmon-exciton coupling is observed in the loss function spectra.