Raman- and Infrared-Active Phonons in Nonlinear Semiconductor AgGaGeS4

Abstract

AgGaGeS4 is an emerging material with promising nonlinear properties in the near- and mid-infrared spectral ranges. Here, the experimental phonon spectra of AgGaGeS4 single crystals synthesized by a modified Bridgman method are presented. The infrared absorption spectra are reported. They are obtained from the fitting of reflectivity to a model dielectric function comprising a series of harmonic phonon oscillators. In the Raman spectra, several modes are registered, which were not detected in previous works. The analysis of the experimental vibrational bands is performed on the basis of a comparison with reported data on structurally related binary, ternary, and quaternary metal chalcogenides. The temperature dependence of the Raman spectra between room temperature and 15 K is also investigated.

Non-Vacuum Fabrication of Bandgap-Controlled CZTGS Alloy Films Using CZTS+CZGS Mixed Nanoparticle Inks

“…Such a characteristic splitting was clearly observed in the Raman spectra of our alloy films of x = 0.22, 0.48, and 0.72, and the relative intensity of a higher frequency peak increases as an exchange of Sn to Ge proceeds. These spectral characteristics, the systematic shift, and the splitting that depend on the composition ratio of Sn/Ge, are in good agreement with the CZTGS single crystals synthesized by a chemical vapour transport [14]. Thus, they provide strong evidence of the formation of CZTGS alloys without any apparent secondary phase and phase separation.…”

“…involved in the alloy. Therefore, in the alloy, the A1 peak splits into two peaks that represent the Snlike mode at a lower frequency and the Ge-like mode at a higher frequency [14]. Such a characteristic splitting was clearly observed in the Raman spectra of our alloy films of x = 0.22, 0.48, and 0.72, and the relative intensity of a higher frequency peak increases as an exchange of Sn to Ge proceeds.…”

Optical properties of γ-sensing β-GaLaS3:Er crystal

“…Moreover, they include components of fully symmetric oscillatory modes A 1 , which, as a rule, are the most intense in the spectra. Comparing these frequencies with our previously published data for quaternary chalcogenides [29,30], all of them can be related to the vibrations of the GaS 4 tetrahedra.…”

“…The structure of these spectra in the range of frequencies >250 cm −1 is entirely related to GaS 4 tetrahedra. The same applies to bands in the region of 120 and 200 cm −1 , as follows from the analysis of spectra of related compounds [29,30].…”

“…From our previous experience of the investigation of Raman and IR spectra of Ga-containing multicomponent chalcogenides AgGaGeS 4 [29] and PbGa 2 GeS 6 [30], their phonon spectra were largely determined by the vibrations of the structural groups formed by GaS 4 tetrahedra.…”