Optical phonons and structure of TlGaS₂, TlGaSe₂, and TlInS₂ layer single crystals

Abstract

The polarization properties of bands in Raman scattering and IR reflection spectra are studied experimentally in TlGaS2, TlGaSe2, and TlInS2 layer single crystals and in solid solutions based on them. Additionally the angular dependence of IR‐active modes on the angle between the phonon wave vector and the direction of the optical axis c of single crystals is investigated. It is shown that the observed phonon spectra can be interpreted on the basis of a primitive cell which contains two tetragonal‐symmetry layers bonded to each other by an inversion operation. Bands corresponding to cells with a mixed composition are observed in the Raman spectra of the solid solutions.

Low-Temperature Raman Scattering in TlGaxIn1-xS2Layered Mixed Crystals: Compositional Dependence of the Mode Frequencies and Line Shapes

“…The phonon spectra of TlGa x In 1−x S 2 mixed crystals at room temperature have been deduced previously from infrared reflection, Raman, and Brillouin scattering measurements [14][15][16]. In our previous paper we reported the frequency dependencies of the Raman-active modes on composition of TlGa x In 1−x S 2 mixed crystals at T = 300 K [14].…”

“…In our previous paper we reported the frequency dependencies of the Raman-active modes on composition of TlGa x In 1−x S 2 mixed crystals at T = 300 K [14].…”

Low-temperature photoluminescence spectra of TlInxGa1−xS2 layer mixed crystals

“…Undoped TlIn,Gai_& mixed crystals were grown by the modified Bridgman method [6]. bands were observed at temperatures higher than Wavelength (nml z220K.…”

Low-temperature visible photoluminescence spectra of TlGaSe2 layered crystal

“…Each successive layer is rotated by a 903 angle with respect to the previous layer. Long-wave optical phonons in these crystals were investigated by infrared re#ection and Raman scattering experiments [5]. Recently, we have studied the photoluminescence (PL) of TlGaS and TlInS single crystals [6,7], and observed broad emission bands, which we have attributed to donor}acceptor pair recombination.…”