Raman Spectral Analysis of Sputtered and Sulfurized Nanostructured WS2 Films

This study presents the Raman spectral characteristics and selected electrical parameter measurements of WS2 films deposited by magnetron sputtering on sapphire and subsequently sulfurized. The analysis of the Raman spectra focuses on the positions and shifts of the E12g and A1g vibrational modes. The effects of different sputtering times on WS2 films and the corresponding activation energy values were also investigated. From both physical and experimental perspectives, the Raman spectral features of WS2 films were found to depend on the laser excitation wavelengths (532 nm and 632.8 nm) as well as on possible crystallographic defects and variations in the excitation point position. These defects have a significant influence on both the Raman spectra and the activation energies of the studied samples. The calculated activation energies (~ 0.15–0.19 eV) of the conduction charge carriers correlate with shallow defect-related energy levels indicated by the Raman characteristics.