Band Structure and Optical Properties οf the Layered Hg3TeCl4Hg_{3}TeCl_{4} Crystal

First experimental investigations on absorption and photoluminescence of the novel $Hg_{3}TeCl_{4}$ monocrystals grown by the Bridgman method are reported. A comparison of the measurement results with theoretical band structure calculations of the $Hg_{3}TeCl_{4}$ crystal confirmed that $Hg_{3}TeCl_{4}$ is a wide-band-gap photoconductor ($E_{g}$ = 3.64 eV at 24 K) with the effective masses of charge carriers characteristic for semiconductors. Energetic position of the main photoluminescence peak and its temperature dependence indicates the presence of an additional energy level in the energy gap which takes part in the radiative recombination process and whose origin was discussed

The In4\text{}_{4}Se3\text{}_{3} Crystal as a Three-Dimensional Imitative Model of Phenomena in One-Dimensional Crystals

For three-dimensional charge carriers described by the dispersion law with quartic terms of the wave vector, the density of states function similar as in the one-dimensional case was determined. This similarity allows the Pekar and Dejgen condenson states in the continuum approximation to exist. The calculated phonon spectrum reveals optical vibrations of a very low frequency, which favours the electron-phonon interaction and creation of the condenson states

Gain Spectrum for the In4\text{}_{4}Se3\text{}_{3} Crystal with a Non-Standard Dispersion Law of Charge Carriers

Based upon the ab initio band structure calculations results and the density of states function of the orthorhombic In$\text{}_{4}$ Se$\text{}_{3}$ crystal as well as the experimental data concerning its radiative recombination, it was shown that the Bernard-Durafour condition is fulfilled for this crystal. The absorption coefficient α that exhibits a negative value in the given energy range and for the given concentrations of non-equilibrium charge carriers, was calculated

Gain Spectrum for the In 4

Based upon the ab initio band structure calculations results and the density of states function of the orthorhombic In$\text{}_{4}$ Se$\text{}_{3}$ crystal as well as the experimental data concerning its radiative recombination, it was shown that the Bernard-Durafour condition is fulfilled for this crystal. The absorption coefficient α that exhibits a negative value in the given energy range and for the given concentrations of non-equilibrium charge carriers, was calculated