Resumo:
The objective of this work is to present the results of the synthesis and characterization
of two-dimensional molybdenum disulfide (MoS2) layers, obtained through the Physical
Vapor Deposition (PVD) technique on silicon dioxide (SiO2) substrates, aiming to evaluate
their potential in thermoelectric applications. MoS2 is a two-dimensional material with
promising electronic and thermal properties, making it a strong candidate for use in energy
conversion devices.
Three distinct experimental approaches were adopted to assess the effects of different
synthesis conditions on the quality of the obtained material. In the first experiment,
thin MoS2 layers were synthesized from commercial MoS2 powder under a sulfur-rich S2
atmosphere using a PVD furnace. In the second, an H2O atmosphere was added along
with S2 to evaluate the effects of this modification on the layer growth. In the third, silver
doping was performed in a tubular furnace to investigate its effects on the structural and
vibrational properties of the material.
The samples were characterized by Optical Microscopy (OM) and Scanning Electron Microscopy
(SEM), used to evaluate the morphology and distribution of the formed layers.
X-ray Diffraction (XRD) was applied for qualitative identification of the crystalline structure,
while Raman Spectroscopy was employed for a detailed analysis of the vibrational
properties of MoS2, with emphasis on the 𝐸1
2𝑔 and 𝐴1𝑔 modes.
The results showed that the presence of H2O during deposition favored the formation of
films with lower structural disorder and higher crystallinity, as evidenced by the enhancement
of characteristic peaks in the XRD and Raman analyses. Silver doping also influenced
the vibrational properties, suggesting changes in the material’s electronic structure.
These findings contribute to the application of MoS2 in electronic and thermoelectric
devices, demonstrating that controlled modifications in the synthesis conditions can significantly
improve its structural quality and functionality.
