Giant Exciton Mott Density in Anatase TiO2

Elucidating the carrier density at which strongly bound excitons dissociate into a plasma of uncorrelated electron-hole pairs is a central topic in the many-body physics of semiconductors. However, there is a lack of information on the high-density response of excitons absorbing in the near-to-mid ultraviolet, due to the absence of suitable experimental probes in this elusive spectral range. Here, we present a unique combination of many-body perturbation theory and state-of-the-art ultrafast broadband ultraviolet spectroscopy to unveil the interplay between the ultraviolet-absorbing two-dimensional excitons of anatase TiO2 and a sea of electron-hole pairs. We discover that the critical density for the exciton Mott transition in this material is the highest ever reported in semiconductors. These results deepen our knowledge of the exciton Mott transition and pave the route toward the investigation of the exciton phase diagram in a variety of wide-gap insulators.


Published in:
Physical Review Letters, 125, 11, 116403
Year:
Sep 10 2020
ISSN:
0031-9007
1079-7114
Keywords:
Note:
Published under the terms of the Creative Commons Attribution 4.0 International license.
Laboratories:


Note: The status of this file is: Anyone


 Record created 2020-09-24, last modified 2020-10-25

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