High temperature Raman investigation of few-layer MoTe2

Abstract

We present a Raman investigation of the temperature effect of single and few layer MoTe2 at an electronic device working temperature range from 300 K to 500 K. We observe linear frequency red-shifts with increasing temperature for the first order Raman active E12g, A1g, Raman inactive B12g mode, and the second order ω2 mode, which can be attributed to the anharmonic effect of the interatomic potential energy. The temperature coefficients of the out-of-plane vibrational B12g modes and inplane vibrational E12g modes are similarly around −0.013 cm−1/K, while lower than that of out-of-plane vibration A1g mode at −0.009 cm−1/K. The temperature coefficient of ω2 mode is −0.00521 cm−1/K, approximately half of those of the first order modes, and the temperature coefficient of transverse acoustic TA (M) mode is indirectly deduced as −0.0102 cm−1/K, which shows the corresponding Mo-Te stretching bonds of TA (M) mode behavior similarly to those of optical Raman vibrations. Our work thus provides temperature dependent lattice vibration information of MoTe2 and could be potentially useful in future optoelectronic devices based on MoTe2 related two dimensional materials.

Highly Anisotropic GeSe Nanosheets for Phototransistors with Ultrahigh Photoresponsivity

“…Then Raman spectroscopy was performed to further investigate the crystal structure of the exfoliated 2D GeSe nanosheets. Figure d illustrates the temperature‐dependent Raman spectra measured at the temperature range from 80 to 500 K, which is a practical way for uncovering the atomic bonds, thermal expansion, and phonon vibration properties of 2D materials . The peak positions around 82.5, 149.2, and 185.9 are corresponding to the A 1 g , B 3g , and A 3 g modes, respectively, in good agreement with the previous reports .…”

Post-patterning of an electronic homojunction in atomically thin monoclinic MoTe 2

“…During laser-irradiation, the local temperature on the top layer was estimated to be around 400 °C, based on the amount of red-shift in the Raman A g and B g peaks (figure 1(c)) [38]. The high temperature heating was conducted in air, and the thickness of the flake gradually decreased and then saturated at 3 layers; at the saturated thickness, the local temperature on the surface cannot be maintained due to rapid heat dissipation into the SiO 2 /Si substrate [39].…”

Bond-photon-phonon thermal relaxation in the M(X, X2) (M = Mo, Re, Ta, Ge, Sn; X = S, Se, and Te)

“…The BOLS reproduction of the measured Raman A 1g modes for (a) few-layer48,49 (FL) and monolayer 48 (ML) MoTe 2 , (b) (Ta, Sn, Re)-Se 2 ,[50][51][52][53][54] and (c) (Sn, Ge)-(S 2 , Se 2 ) 44. Theoretical reproduction of the measured Raman E 1 2g modes for (a) monolayer32,49 (ML), bilayer32,48 (BL), and few-layer48,49 (FL) MoTe 2 , (b) (Ta, Sn, Re)-Se 2 . 50-53 This journal is © The Royal Society of Chemistry 2020 RSC Adv., 2020, 10, 5428-5435 | 5431 Paper RSC Advances Open Access Article.…”