Excitons in gallium sulphide

Abstract

Strong evidences for existence of indirect excitons in Gas are obtained a s a result of an analysis of differential absorption and photoluminescence spectra registered in the 4.2 to 100 K temperature range in polarized light. The location of the exciton band in gallium sulphide E,,, = = (2594 & 2) meV and the energy of phonons which take part in indirect transitions are determined. Lines which are interpreted as a result of non-phonon transitions are observed in the absorption and emission spectra. Lines which arise from the decomposition of bound excitons are found in emission spectra as well. It is shown that polarization pecularities of Gas absorption and luminescence spectra are explained in terms of the band scheme of gallium selenide which is structurally analogous to Gas. The possible nature of the anisotropy of excitons in Gas is discussed.

Exciton Absorption and Luminescence of Indium Selenide Crystals

“…The increase of the crystal lattice temperature will result in blurring the fine structure due t o the appearance of rigid layer modes. [4] are not yet observed. For comparison (cf.…”

Photoluminescence of layered semiconductor GaS doped with Mn

“…The peak energies due to the impurity band [12] and donor -acceptor transitions decrease with E g as the temperature increases [13]. Belenkii and Godzhaev have reported that in GaS the impurity luminescence besides the free and bound indirect excitons originate from the donor-acceptor recombination [10]. We suppose that the radiative recombination of the PB emission band is related to the donor-acceptor pair.…”

“…Belenkii and Godzhaev have shown that the PA emission band is due to the radiative recombination related to the indirect bound exciton [10]. The bound exciton with a binding energy of 14 meV takes place simultaneously with a phonon energy of 10 meV.…”

“…We evaluated E g from the bound exciton peak energy. Values of 14 meV for the binding energy and 10 meV for the phonon energy were used in the calculation [10]. The calculated values are indicated by open squares in the figure.…”

Radiative centers in layered semiconductor GaS doped with Zn

“…The PA emission band is due to the radiative recombination related to the indirect band exciton. This indirect band exciton with a binding energy of 14 meV recombines simultaneously emitting a phonon energy of 10 meV [10]. We postulate that the other four emission bands are related to the indirect band exciton with the phonon emission.…”