Lattice Vibration of Layered GaTe Single Crystals

Abstract

Abstract:The effect of interlayer interaction on in-layer structure of laminar GaTe crystals was studied according to the lattice vibration using micro-Raman analysis. The results were also confirmed by the first principle calculations. Accordingly, the relationship between lattice vibration and crystal structure was established. Ten peaks were observed in the micro-Raman spectra from 100 cm −1 to 300 cm −1 . Eight of them fit Raman-active vibration modes and the corresponding displacement vectors were calculated, which proved that the two modes situated at 128.7 cm −1 and 145.7 cm −1 were related to the lattice vibration of GaTe, instead of impurities or defects. Davydov splitting in GaTe was identified and confirmed by the existence of the other two modes, conjugate modes, at 110.7 cm −1 (∆ω = 33.1 cm −1 ) and 172.5 cm −1 (∆ω = 49.5 cm −1 ), indicates that the weak interlayer coupling has a significant effect on lattice vibrations in the two-layer monoclinic unit cell. Our results further proved the existence of two layers in each GaTe unit cell.

Passivation of Layered Gallium Telluride by Double Encapsulation with Graphene

“…The origin of these modes is still the subject of some controversy. Some previous first-principles calculations have suggested that these modes can be attributed to first 42 or second-order 15 Raman-active phonon modes, whereas other groups have claimed that they appear only as the products of the GaTe oxidation process. 19,25,26 In the latter case, the similarities to both TeO 2 and aged Raman spectra of other Te-containing compounds have been noted, 19 supporting the idea that the 129 and 144 cm –1 peaks result from the oxidation of Te atoms at the sample surface.…”

“…The freshly cleaved sample shows prominent peaks at 109, 115, 162, 176, 210, 270, and 283 cm –1 in good agreement with previous reports. 25,26,42 Aged flakes exhibit only two peaks at 129 and 144 cm –1 . The origin of these modes is still the subject of some controversy.…”

Lattice Dynamics and Thermodynamic Properties of Bulk Phases and Monolayers of GaTe and InTe: A Comparison from First‐Principles Calculations

“…Several experimental works have been devoted to the study of vibrational properties of stable gallium and indium tellurides. Most of them [33][34][35][36][37][38] consider the lattice vibrations of GaTe. Raman (R) active modes have been determined in Refs.…”

“…Raman (R) active modes have been determined in Refs. [33,37,38], infrared (IR) reflection spectrum has been measured in Refs. [35,36], and both R and IR frequencies of GaTe were obtained in Refs.…”

“…Authors of Ref. [38], besides the experimental measurements, perform the density functional theory (DFT) calculations intending to assign the experimental frequency values. The only known for us report on the InTe Raman spectrum was published by Nizametdinova.…”