The far-infrared absorption spectrum of electron-hole drops in silicon

Terahertz Luminescence Induced by Intra‐Exciton Radiative Transitions in Silicon

“…The THz absorption by means of the plasma oscillations in EHL drops, observed in ref. , was comparable in intensity to the free exciton absorption. Therefore, the absence of the emission line associated with plasma oscillations in spectra of the THz PL from Si indicates the low efficiency of such a channel for THz luminescence in comparison with intra‐exciton optical transitions.…”

“…We attribute such a non‐monotonic behavior of excitonic THz PL to the formation of EHL drops in the Si crystal at temperatures near the liquid helium temperature at sufficiently high interband excitation densities . It is worth to note that the excitation density of 140 W cm −2 is well above the EHL formation threshold in high‐purity Si crystals at helium temperatures . Under these conditions, as the temperature increases from 5 to 16 K, the concentration of free excitons in the crystal increases because of their evaporation from the surface of EHL drops.…”

“…It should be noted that there is no emission line at the energy of about 34 meV in the THz PL spectra (Figure ) although that could occur in accordance with the data of ref. . This paper reported on the observation of a THz absorption line at 34.2 meV associated with excitation of plasma oscillations in EHL drops in silicon.…”

“…A series of spectra of the THz PL from a high‐purity Si crystal for different temperatures and a photoexcitation density of 0.1 W cm −2 is shown in Figure . Since the intensity of the interband pumping is only 0.1 W cm −2 , the formation of electron‐hole liquid (EHL) from excitons in Si does not happen in these conditions . In the spectrum of THz emission at T = 5 K (see Figure ), intense narrow lines with maxima at 10.2, 11.4, and 12.1 meV are clearly visible (the observed spectral widths (FWHM) of these lines are 0.55, 0.52, and 0.52 meV, respectively, and mainly determined by the spectrometer).…”

The electron-hole liquid in a semiconductor

“…нородно сжатом Ge 305 . Плазменный резонанс на ЭДК был обнаружен и в Si 306 . В заключение укажем, что исследование поглощения и фотопроводимо-сти в субмиллиметровой области (т. е. в диапазоне йш ~ Е ех ) является прямым и очень чувствительным способом исследования спектра и концен-трации свободных экситонов (см., например, 42 ).…”