https://doi.org/10.1140/epjd/s10053-024-00814-w
Regular Article - Optical Phenomena and Photonics
Exciton-to-plasma Mott crossover in silicon
Indian Institute of Science Education and Research Kolkata, 741246, Mohanpur, Nadia, West Bengal, India
Received:
20
June
2023
Accepted:
29
January
2024
Published online:
1
March
2024
Excitonic Mott transition is a many-body crossover phenomenon where, even at zero temperature, a gas of excitons is expected to spontaneously ionize as its density or pressure is increased. Although this ionization due to the disappearance of the bound states from the energy spectra has long been predicted and continues to be studied, compelling demonstrations have been missing and the exact mechanism remains controversial. We revisit the phenomenon for silicon and report a number of striking features. The low temperature photoluminescence spectrum, around a certain crossover density shows a decrease in the emission intensity with increase in the excitation power. The photoluminescence efficiency (emission per incident photon) decreases by more than an order of magnitude building up to the Mott crossover, after which it becomes almost constant. This drastic loss in the oscillator strength is accompanied onset of a strong broadening of the excitonic peak. A comparison of this low temperature excitation power-dependent behavior of the photoluminescence emission with its temperature dependent change rules out the observations being explained by just the laser-induced heating of the sample.
Supplementary Information The online version contains supplementary material available at https://doi.org/10.1140/epjd/s10053-024-00814-w.
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