## 3 Results and Discussion
### Characterization of Morphology and Chemical States of Polycrystalline Diamond Films
#### 3.1.4 Raman Analysis
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Samples**} & **Fit** & **v1** & **Diamond** & **D* & **v2** & **G** & **(v1 + v2)** & **(D* + G)** \\  & **Parameters** & **1150 cm\({}^{-1}\)** & **1332 cm\({}^{-1}\)** & **1350 cm\({}^{-1}\)** & **1480 cm\({}^{-1}\)** & **1580 cm\({}^{-1}\)** & **\%** & **\%** \\ \hline \multirow{2}{*}{A} & Center & 1161 & & 1345 & 1487 & 1572 & 14\% & 86\% \\ \cline{2-8}  & FWHM & 80 & & 160 & 100 & 110 & & \\ \hline \multirow{2}{*}{B} & Center & 1147 & & 1343 & 1474 & 1559 & 40\% & 60\% \\ \cline{2-8}  & FWHM & 90 & & 110 & 120 & 120 & & \\ \hline \multirow{2}{*}{C} & Center & 1136 & 1333 & 1358 & 1473 & 1537 & 38\% & 60\% \\ \cline{2-8}  & FWHM & 50 & 10 & 130 & 100 & 114 & & \\ \hline \multirow{2}{*}{D} & Center & 1134 & 1334 & 1358 & 1466 & 1553 & 56\% & 36\% \\ \cline{2-8}  & FWHM & 40 & 12 & 80 & 120 & 80 & & \\ \hline \multirow{2}{*}{E} & Center & 1263 & 1334 & 1374 & 1467 & 1566 & 40\% & 48\% \\ \cline{2-8}  & FWHM & 44 & 15 & 69 & 120 & 100 & & \\ \hline \multirow{2}{*}{F} & Center & 1270 & 1332 & 1376 & 1460 & 1562 & 31\% & 61\% \\ \cline{2-8}  & FWHM & 54 & 8 & 80 & 120 & 160 & & \\ \hline \multirow{2}{*}{G} & Center & 1285 & 1332 & 1367 & 1460 & 1555 & 30\% & 62\% \\ \cline{2-8}  & FWHM & 120 & 8 & 80 & 120 & 160 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Deconvoluted parameters of the Raman spectra using a Lorentzian distribution function. It is expected that the contribution of v1 and v2 decreases with large grain sizes (Figure 7c purple arrow) since the H atom concentration decreases. The reduction in the TPA signal from NCD to UNCD (Figure 7 purple arrows from (b) to (a)) and the fact that H\({}_{2}\) flow is lower during the growth of UNCD may suggest that there are not enough H atoms to saturate all the dangling bonds in the diamond crystals. This will make the C=C more common at the surface of the diamond grain and with the adjacent diamond grain. The initial UNCD growth forms hemispherical structures which then merge into a continuous film. The large presence of D* and G for UNCD could be due to filling between the cluster of crystals (up to \(\sim\)1 \(\upmu\)m) that is typical in UNCD film growth [12,26]. Interestingly, the signal from the silicon carbide nucleation layer on the Si substrate (white arrows) was higher for PCD films with intermediate thickness (Figure 7b) than for either much thinner PCD (Figure 7a) or thicker PCD films (Figure 7c). The hypothesis is that for the UNCD film-type samples the high degree of absorption prevented penetration into the SiC nucleation layer. For the thick PCD films, correlating with MCD, the signal corresponding to SiC was reduced simply due to the depth of the SiC layer from the surface of the PCD film. Using the diagram as a representation of the grain growth, all samples started with smaller grains at the nucleation site. The SIMS data (Figure 4b) show a decrease in H atom concentration going from the substrate to the surface. The smaller crystals, especially near the substrate, have a greater grain boundary surface area and thus a higher H atom concentration. This effect is consistent with the proposed model, which attributes the H incorporation primarily to the passivation of dangling C bonds at the grain boundaries. Atomic Force Microscopy-Based Characterization of Surface Structure and Associated Electrical Performance of PCD Films  
2.1 Conductive Atomic Force Microscopy (CAFM) Measurements of Electrical Conduction through PCD Films  
Figure 8 shows AFM measurements of electrical conduction through the PCD films using the CAFM mode to measure electrical conduction through an MCD film (sample F in Table 1). Figure 7: Schematic showing 532 nm wavelength laser beam interaction with (**a**) UNCD, (**b**) NCD, and (**c**) MCD films grown on Si substrates. For UNCD films the laser light is mostly absorbed by C atoms, with sp\({}^{2}\) bonds making this signal the highest contribution.