A great deal of research has been carried out on low-dimensional transition-metal dichalcogenides (TMDs) because of their versatile properties and numerous applications. Among TMDs, molybdenum ditelluride (MoTe2) has garnered significant attention as a ‘beyond graphene’ material because of its extraordinary structural and physical characteristics. To characterize the microstructural properties of low-dimensional TMDs, Raman spectroscopy can be adopted as a non-destructive characterization technique because of its various advantages. In this work, the impact of post-growth temperature and growth parameters of MoTe2 was studied using Raman spectroscopy. Variations in Raman peak intensity were correlated with the formation and dissociation of Mo–Te bonds. With increasing growth temperature and duration, a transition in peak intensities was observed, typically characterized by a decrease in Te-related peaks and a relative increase in MoTe2 peaks. As the growth duration increased, the Te Raman-active modes vanished and the MoTe2 Raman-active modes appeared. The absence of MoTe2 Raman peaks at low temperatures was attributed to insufficient thermal energy for crystallization. Films annealed at 625 °C for 1 h under the specified conditions did not exhibit tellurium peaks, indicating effective conversion to MoTe2; however, this outcome may vary with different annealing parameters. Longer annealing durations enhanced the intensity of the E12g and B12g Raman peaks, indicating improved crystallinity. As the number of layers increased with longer sputtering times, the E12g and B12g peaks shifted to lower wavenumbers, accompanied by a reduction in full width at half maximum (FWHM). Conversely, a decrease in MoTe2 layers caused these peaks to shift to higher wavenumbers and the FWHM to broaden. X-ray diffraction (XRD) analysis revealed peaks at approximately 12.8°, 25.5°, 39.2°, and 53.2°, corresponding to the (002), (004), (006), and (008) planes, respectively. Atomic force microscopy (AFM) studies confirmed homogeneous film deposition, characterized by distinct hills and valleys on the surface. The current–voltage (I–V) study demonstrated the rectifying nature of the MoTe2/Si heterojunction, with a rectification ratio of approximately 102. Further, the I–V and current–time (I–t) characteristics were evaluated under different infrared (IR) illumination conditions. The maximum responsivity and detectivity were found to be 1.59 A W−1 and 2.2 × 109 jones, respectively, at an IR wavelength of 1060 nm. Additionally, the rise and fall times of the device were measured to be 0.98 s and 1.11 s, respectively, demonstrating its potential for IR detection applications. Hence, this extensive study of Raman-active modes in MoTe2 provides valuable insight into the fabrication of high-quality low-dimensional TMD-based high-performance devices.

Investigation of Raman spectral characteristics with variation of RTP process parameters

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发表日期：

2026年2月3日

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Anurag Gartia,
Diana Pradhan,
Kiran Kumar Sahoo,
Sameer Ranjan Biswal,
Somesh Sabat,
Tanmoy Parida,
Raghvendra S Saxena,
Pawan Kumar,
Jyoti Prakash Kar

摘要

A great deal of research has been carried out on low-dimensional transition-metal dichalcogenides (TMDs) because of their versatile properties and numerous applications. Among TMDs, molybdenum ditelluride (MoTe₂) has garnered significant attention as a ‘beyond graphene’ material because of its extraordinary structural and physical characteristics. To characterize the microstructural properties of low-dimensional TMDs, Raman spectroscopy can be adopted as a non-destructive characterization technique because of its various advantages. In this work, the impact of post-growth temperature and growth parameters of MoTe₂ was studied using Raman spectroscopy. Variations in Raman peak intensity were correlated with the formation and dissociation of Mo–Te bonds. With increasing growth temperature and duration, a transition in peak intensities was observed, typically characterized by a decrease in Te-related peaks and a relative increase in MoTe₂ peaks. As the growth duration increased, the Te Raman-active modes vanished and the MoTe₂ Raman-active modes appeared. The absence of MoTe₂ Raman peaks at low temperatures was attributed to insufficient thermal energy for crystallization. Films annealed at 625 °C for 1 h under the specified conditions did not exhibit tellurium peaks, indicating effective conversion to MoTe₂; however, this outcome may vary with different annealing parameters. Longer annealing durations enhanced the intensity of the E¹_2g and B¹_2g Raman peaks, indicating improved crystallinity. As the number of layers increased with longer sputtering times, the E¹_2g and B¹_2g peaks shifted to lower wavenumbers, accompanied by a reduction in full width at half maximum (FWHM). Conversely, a decrease in MoTe₂ layers caused these peaks to shift to higher wavenumbers and the FWHM to broaden. X-ray diffraction (XRD) analysis revealed peaks at approximately 12.8°, 25.5°, 39.2°, and 53.2°, corresponding to the (002), (004), (006), and (008) planes, respectively. Atomic force microscopy (AFM) studies confirmed homogeneous film deposition, characterized by distinct hills and valleys on the surface. The current–voltage (I–V) study demonstrated the rectifying nature of the MoTe₂/Si heterojunction, with a rectification ratio of approximately 10². Further, the I–V and current–time (I–t) characteristics were evaluated under different infrared (IR) illumination conditions. The maximum responsivity and detectivity were found to be 1.59 A W⁻¹ and 2.2 × 10⁹ jones, respectively, at an IR wavelength of 1060 nm. Additionally, the rise and fall times of the device were measured to be 0.98 s and 1.11 s, respectively, demonstrating its potential for IR detection applications. Hence, this extensive study of Raman-active modes in MoTe₂ provides valuable insight into the fabrication of high-quality low-dimensional TMD-based high-performance devices.