# Correlating Disorder Microstructure and Magnetotransport of Carbon Nanowalls
## 2 Experimental Section  
Previous studies [26; 27; 28] have found the key to control different characteristics on the carbon nanowalls (such as length, shape and composition) through the synthesis parameters by the PECVD. We apply the following constant parameters: pressure of 120 Pa and RF power of 300 W, hydrogen/acetylene H\({}_{2}\):C\({}_{2}\)H\({}_{2}\) = 25:1 sccm and Si/SiO\({}_{2}\) substrate placed at 5 cm from expansion nozzle. Table 1 shows the parameters that were varied: the ratio Argon flux at 1050 and 1400 sccm, the deposition time at 30 and 60 min, and the deposition temperature \(T_{D}=600\)\({}^{\circ}\)C and \(T_{D}=700\)\({}^{\circ}\)C. In the following, we named the samples formed at 1400 sccm-600 \({}^{\circ}\)C-1 h and 1400 sccm-700 \({}^{\circ}\)C-1 h Sample I and Sample II, respectively, due to the relevant structural and morphological characteristics to the magnetotransport studies.  
The shape and the space between the walls of CNWs were observed by Scanning Electron Microscope (SEM), using an SEM 630 FEI Nova Nano at 10\({}^{-4}\) mbar and Transmission Electron Microscope (TEM) with a JEOL 2010-F Field Emission of high resolution, operating at 200 kV. The Raman spectrum was obtained with a \(\lambda_{laser}=632.8\) nm, using a Horiba-Jobin-Yvon HR LabRAM. The Elastic Recoil Detection Analysis (ERDA) shows the hydrogen in-depth profile and concentration using 3 MeV 4 He\({}^{2+}\) ions from a 3 MV Tandetron accelerator.  
Figure 1 shows the configuration of the MR measurement, where the CNWs' samples were synthetized on four consecutive chrome-gold electrodes. The metallic strips had a gap of around 1 mm. The spacing and length of the electrodes were chosen to study the MT across a large number of CNWs junctions. The MR measurements were performed by injecting a constant electric current of 5 mA (the high value was selected due to the elevated number of walls between the electrodes). The MR behavior was not clear with values that were too small (below 1 mA). An externally relatively high magnetic field B ranging from 0 to 7 T, perpendicular to the sample's surface (parallel to the graphene layers), was applied. The temperature for measurements varied between 15 and 250 K. The MR was calculated as follows:  
\[MR=\frac{R(B)-R(0)}{R(0)}\cdot 100\% \tag{1}\]  
where \(R(B)\) is the resistance with the magnetic field applied, while \(R(0)\) is the resistance in the absence of magnetic field.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \multirow{2}{*}{**Synthesis Parameters**} & **Time (min)** & **30** & \multicolumn{3}{c}{**60**} \\ \cline{2-7}  & **Temperature (\({}^{\circ}\)C)** & **700** & \multicolumn{3}{c}{**600**} & \multicolumn{3}{c}{**700**} \\ \cline{2-7}  & **Ar Flux (sccm)** & **1400** & **1050** & **Sample I 1400** & **1050** & **Sample II 1400** \\ \hline \multirow{8}{*}{**Morphology and Microstructure**} & Length (\(\mu\)m) \(\pm\)0.3 & 0.23 & 1.05 & 1.5 & - & 1.3 \\ \cline{2-7}  & Thickness (\(\mu\)m) & 0.50 & 1.50 & 3.05 & - & 1.52 \\ \cline{2-7}  & \(l(D)/l(G)\) & 2.40 & 1.81 & 1.80 & 2.21 & 2.20 \\ \cline{2-7}  & \(l(D)/l(D^{\prime})\) & 4.8 & 5.5 & 3.2 & 4.4 & 5.5 \\ \cline{2-7}  & \(L_{a}\) (nm) & 20.4 & 21.0 & 21.1 & 17.2 & 17.3 \\ \cline{2-7}  & \(L_{D}\) (nm) & 11.5 & 11.7 & 11.8 & 10.6 & 10.6 \\ \cline{2-7}  & 2D Position (cm\({}^{-1}\)) & 2646 & 2651 & 2646 & 2649 & 2639 \\ \cline{2-7}  & Carbon Concentration (\%) by XPS & - & 64.64 & 86.44 & 55.50 & 74.93 \\ \cline{2-7}  & Oxygen Concentration (\%) by XPS & - & 35.36 & 13.56 & 44.50 & 25.07 \\ \cline{2-7}  & Hydrogen Content & 1.4 & 16.7 & 9.1 & 10.1 & 7.8 \\ \cline{2-7}  & by ERDA & & & & & \\ \hline \end{tabular}
\end{table}
Table 1: Values obtained from SEM, TEM, ERDA and Raman spectra of the CNWs formed at different synthesis parameters: time, deposition temperature and Ar flux.