7–10 Sept 2020
Europe/Zurich timezone
20. konference českých a slovenských fyziků

NOVEL DIRECTIONS IN STUDIES OF ELECTRON-HOLE LIQUID IN SEMICONDUCTORS: WIDE GAP AND 2D MATERIALS

9 Sept 2020, 14:05
40m
lecture hall T1 (building A)

lecture hall T1

building A

Speaker

Valenta J. (katedra chemické fyziky a optiky, Matematicko-fyzikální fakulta, Univerzita Karlova, Praha)

Description

The low-temperature electron-hole plasma may undergo phase transition to the liquid state:
the electron-hole liquid (EHL). The transition is allowed in dense plasma below critical
temperature T C and it exists only in the thermodynamic limit, i.e. when the lifetime of the
electron-hole system is long enough to reach the thermal equilibrium. For that reason, the
macroscopic and relatively long-lived EHL is exclusively observed in the indirect
semiconductors. This liquid phase is the two component degenerate Fermi liquid. EHL has a
form of spatially separated “droplets” within a cloud of EHP or excitons. In close analogy
with conventional liquids EHL has constant density at given temperature – it is related to the
quasiparticle distance for which their energy is minimized. Decay of EHL droplets via
electron-hole recombination is faster than decay of free excitons - fortunately, this decay
includes radiative recombination processes giving rise to photoluminescence (PL) which is
the most important messenger bringing information on EHL. The investigation of the
intriguing new “matter” was conducted mostly in 1970ies in Si and Ge. EHL was later
observed also in low-dimensional semiconductor structures. Here we present recent results on
wide-gap semiconductors (especially 4H-SiC) and the graphene-like materials like MoS 2 .

Primary author

Valenta J. (katedra chemické fyziky a optiky, Matematicko-fyzikální fakulta, Univerzita Karlova, Praha)

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