# Raman Spectra of ZrS\({}_{2}\) and ZrSe\({}_{2}\) from Bulk to Atomically Thin Layers
## Appendix C Raman Spectra  
Raman spectra with a broader spectral window for ZrS\({}_{2}\) are presented in Figure 11. All spectra for thin layers have been normalized to the silicon phonon peak, which appears at 520.71 \(\pm\) 0.03 cm\({}^{-1}\), except for the spectrum of bulk crystal, which has been normalized to the A\({}_{1g}\) peak. Figure 11: Thickness dependence of the Raman spectra for ZrS\({}_{2}\) (\(\lambda\) = 532 nm) (**a**) on a silicon substrate with 285 nm of SiO\({}_{2}\) and (**b**) on a silicon substrate covered with Ta (3 nm)/Au (30 nm). The Raman modes A\({}_{1g}\) and E\({}_{g}\) are labeled. The shoulder marked with \"\" is attributed to a broadening of the A\({}_{1g}\) peak due to non-harmonic effects. Figure 10: (**a**) Optical microscope and (**b**) AFM measurement of the dotted box in (**a**) with (**c**) the corresponding thickness profile for ZrSe\({}_{2}\) flakes. Figure 12 corresponds to the bare spectra (in counts/s) for ZrS\({}_{2}\) on a Si/SiO\({}_{2}\) substrate without the normalization to the Si phonon peak, in contrast to the spectra shown in Figure 3 and Figure 13. The corresponding values for the fitting of the \(\mathrm{E_{g}}\) and \(\mathrm{A_{1g}}\) are summarized in Table 1. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Thickness**} & \multicolumn{3}{c}{**Eg**} & \multicolumn{3}{c}{\(\bullet\)} & \multicolumn{3}{c}{\(\mathbf{A_{1g}}\)} \\ \cline{2-10}  & **Position** & **Intensity** & **FWHM** & **Position** & **Intensity** & **FWHM** & **Position** & **Intensity** & **FWHM** \\
**(\(\pm 1\) Layer)** & **Position** & **Intensity** & **FWHM** & **Position** & **Intensity** & **FWHM** & **Position** & **Intensity** & **FWHM** \\
108 L & 249.84 \(\pm\) 0.17 & 6.1 & 18.3 \(\pm\) 1.0 & 320.5 \(\pm\) 0.5 & 42.5 & 10.1 \(\pm\) 1.2 & 334.5 \(\pm\) 0.2 & 63.6 & 23.2 \(\pm\) 1.0 \\
55 L & 250.8 \(\pm\) 0.2 & 2.6 & 17.1 \(\pm\) 1.2 & 320.2 \(\pm\) 2 & 19.6 & 7.5 \(\pm\) 0.5 & 334.8 \(\pm\) 0.2 & 31.5 & 23.7 \(\pm\) 1.0 \\
22 L & 250.5 \(\pm\) 0.3 & 2.3 & 20.1 \(\pm\) 1.9 & 320.5 \(\pm\) 0.3 & 19.1 & 8.0 \(\pm\) 0.5 & 335.5 \(\pm\) 0.2 & 29.4 & 24.6 \(\pm\) 0.9 \\
9 L & - & - & - & 321 \(\pm\) 2 & 2.1 & 10 \(\pm\) 4 & 333.9 \(\pm\) 0.5 & 2.9 & 25 \(\pm\) 3 \\
7 L & - & - & - & 319 \(\pm\) 0.9 & 1.7 & 14 \(\pm\) 4 & 335.3 \(\pm\) 0.8 & 2.1 & 30 \(\pm\) 4 \\
4 L & - & - & - & 320 \(\pm\) 3 & 1.2 & 13 \(\pm\) 4 & 336.1 \(\pm\) 1.4 & 1.7 & 12 \(\pm\) 2 \\
2 L & - & - & - & 319 \(\pm\) 5 & 0.7 & 100 \(\pm\) 700 1  & 334.5 \(\pm\) 1.6 & 1.1 & 50 \(\pm\) 201  \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Thickness dependence of the fitted parameters (position, intensity, and FWHM) of the \(\rm E_{g}\) and \(\rm A_{1g}\) modes obtained from the Raman spectra for ZrS\({}_{2}\) on a Si/SiO\({}_{3}\) substrate (\(\lambda\) = 532 nm) presented in Figure 2.  
In Figure 13, the Raman bare spectra (in counts/s) for flakes with different thicknesses of ZrS\({}_{2}\) are shown. Due to the overlapping between the silicon peak and the A\({}_{\text{1g}}\) peak of ZrS\({}_{2}\), Raman spectra of thin flakes of ZrS\({}_{2}\) were studied on a silicon substrate covered with Ta (3 nm)/Au (30 nm). The corresponding values for the fitting of the E\({}_{\text{g}}\) and A\({}_{\text{1g}}\) are summarized in Table 12.  
Raman spectra with a broader spectral window for ZrSe\({}_{2}\) are presented in Figure 14. All spectra have been normalized to the silicon phonon peak, which appears at 520.71 \(\pm\) 0.03 cm\({}^{-1}\). Figure 15 corresponds to the bare spectra (in counts/s) for ZrSe\({}_{2}\) on a Si/SiO\({}_{2}\) substrate without the normalization to the Si phonon peak, in contrast to the spectra shown in Figure 4 and Figure 14. The corresponding values for the fitting of the E\({}_{\rm g}\) and A\({}_{\rm 1g}\) are summarized in Table 13.  
Figure 15: Thickness dependence of the Raman spectra for ZrSe\({}_{2}\) on a Si/SiO\({}_{2}\) substrate (\(\lambda\) = 638 nm).