## 3 Results
However, interesting results were found in the electrical properties results. First, in the case of carrier concentration, an improvement was observed with the increase of the CNT content forming the MWCNT-based buffer layer compared to the pristine CNW. The carbon buffer layer, which plays an important role in the general CNW nucleation and growth mechanism, is an amorphous carbon layer, so excellent electrical properties cannot be expected. While the MWCNT-based buffer layer has better electrical properties than the amorphous carbon layer, it is considered to contribute to the improvement of carrier concentration because it contains many carriers as a semiconductor impurity concept. Second, the carrier mobility was found to be inversely proportional to the carrier concentration. This phenomenon may be caused by alignment and defects in the carbon lattice. The MWCNT-based buffer layer underneath the CNW also has a high carbon lattice disorder similar to that of the CNW, which can significantly affect carrier mobility. The resistivity characteristic was analyzed to decrease with the increase of CNT content. This is because the carrier concentration is dominant in resistive properties, and the increase in the number of carriers by the CNT is expected to lead to a decrease in the resistivity. For this reason, samples containing 70 uL of CNTs showed the outstanding carrier concentration and resistivity. Figure 3: Structural properties results of all samples: (**a**) Raman spectra; (**b**) I\({}_{\text{D}}\)/I\({}_{\text{G}}\) ratio. Figure 5 shows the I-V characteristics of pristine CNW, MWCNT (30 \(\upmu\)L)/CNW, MWCNT (50 \(\upmu\)L)/CNW and MWCNT (70 \(\upmu\)L)/CNW samples. As shown in Figure 1c, four probe tips were contacted at the edge of a sample having a size of 1 cm \(\times\) 1 cm to apply a voltage of \(-\)1 mV to +1 mV. The slopes of the curves were different for all samples, but a linear I-V curve was observed. Since the slope of the curve represents the measured resistance value, it does not have much significance for the stability of the electrical characteristics. However, linearity is the most important factor because it implies that a constant current and resistance are maintained whenever the applied voltage changes. The V-I characteristics appear that all samples are electrically stable, which is due to ohmic contacts, not schottky contacts. Figure 6 shows the change in resistance with the applied current as an I-R characteristic and average \(\upDelta\)R with percentage. An important factor of the I-R characteristics is linearity. This is because the resistance does not change even when the current changes, which means that it is electrically stable. In pristine CNW, parabolic curves were observed in all sections, indicating that there is a change in resistance due to current changes, suggesting this sample is not stable. In the CNW sample formed on the MWCNT-based buffer layer, the improved linearity occurred. As the CNT content was increased, the linearity was dramatically improved. As shown in Figure 6d, the I-R characteristics with a CNT content of 70 \(\upmu\)L show highly improved linearity. However, in Figure 6b,c, partial nonlinearities have been identified. It is noted that these phenomena may be caused by structural changes in CNTs and CNWs, and defects caused by various factors. Figure 4: Electrical properties of all samples: (**a**) carrier concentration and carrier mobility; (**b**) resistivity of all samples. Figure 5: Electrical stability with I-V curve of all samples: (**a**) pristine CNW; (**b**) MWCNT (30 \(\upmu\)L)/CNW; (**c**) MWCNT (50 \(\upmu\)L)/CNW; (**d**) MWCNT (70 \(\upmu\)L)/CNW. In addition, stability test was conducted by obtaining the average \(\Delta\)R at all points of each sample, and it means the better stability with lower \(\Delta\)R. As expected, the pristine CNW showed the largest \(\Delta\)R because the amorphous carbon was formed into the buffer layer, causing the charge transfer to be inconsistent.