GROWTH OF CARBON NANOTUBES (CNT) USING NICKEL CATALYST WITH THE HWC-IN PLASMA-VHF-PECVD METHOD AND APPLICATION ON P-I-N SILICON SOLAR CELLS

• Main Author: Ruslan, Rustan
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/86917
• Institution: Institut Teknologi Bandung

Carbon nanotube (CNT) has become one of the intensive subjects in nanotechnology and advanced materials research because it offers several unique characteristics that are attractive for various applications in electronic and optical devices. One important aspect in the growth of CNT is the role of the catalyst, which serves as a guiding medium in the CNT growth process. To obtain a good catalyst, several optimizations need to be carried out in the growth of catalyst particles, including optimization of layer thickness and optimization of the temperature and annealing time of the catalyst. In this study, the growth of the catalyst using the thermal evaporation method was carried out on a 7101glass substrate with nickel (Ni) as the source material. Nickel is used as a catalyst because it has a good carbon solubility level and a high carbon diffusion value, making it suitable for CNT growth. This research started with optimizing the layer thickness in the growth of Ni catalyst with thickness variations of 30, 40, 50, and 60 nm. In this growth, the optimum thickness was obtained at 50 nm with an average diameter of 40.29 ± 3.22 nm and a low polydispersity of 0.23% compared to other thicknesses. The polydispersity index is related to the level of homogeneity of a sample, which means that the smaller the polydispersity, the better the homogeneity or uniformity of the sample's particles. The EDS results also show a linear relationship between the layer thickness and its mass and atomic content, indicating that the mass and atomic percentage of the nickel catalyst increase with the layer thickness. From the optimum thickness obtained, it was then used and annealing temperature optimization was performed with variations of 300°C, 400°C, and 500°C for 4 hours. Annealing is performed with the aim of improving the crystal structure of the catalyst, resulting in small and uniform grains. Nickel catalyst samples with a thickness of 50 nm that were annealed at a temperature of 300°C showed a smoother surface morphology because during annealing, nickel undergoes structural improvement and at that temperature, it is not sufficient for nickel to form particles or grains. When the temperature is raised to 400°C, larger grains begin to form, but on the other hand, there are still some empty areas. When annealed at a temperature of 500°C, the resulting grains are smaller and more uniform. From the optimization of the annealing temperature conducted, the optimum temperature was obtained at 500°C for 4 hours with an average diameter of 24.85 ± 0.48 nm and a polydispersity of 1.14%. Next, variations in annealing time at the optimum temperature were conducted for 3 and 5 hours, resulting in average Ni catalyst diameters of 27.73 ± 1.02 nm and 19.17 ± 0.3 nm with polydispersions of 2.18% and 1.42%, respectively. These results indicate that an increase in annealing time results in a smaller catalyst diameter. The process of growing carbon nanotubes (CNTs) on Ni catalyst with 3 variations of annealing time was successfully grown at a low temperature of 170°C with 2 hot wire (HW) voltage treatments of 3.5 V and 6 V, which were identified as CNTs even though the growth was not evenly distributed throughout the sample, both horizontally and vertically. At HW voltage of 3.5 V, the diameters of the obtained CNTs were 28.04 ± 2.76 nm, 26.78 ± 1.69 nm, and 20.71 ± 0.78 nm, respectively. Meanwhile, under the growth conditions with an HW voltage of 6 V, the CNT sample with Ni catalyst annealed for 3 hours did not successfully deposit on the substrate (the sample delaminated), and the CNT samples with Ni catalyst annealed for 4 and 5 hours had average diameters of 25.22 ± 1.09 nm and 19.45 ± 0.21 nm, respectively. The application of CNT on p-i-n silicon solar cells has been successfully carried out. The measurement results show quite good outcomes with the formation of an internal electric field, with a VOC of 0.9 V and an JSC of 2.72 mA. Then, a fill factor (FF) value of 0.43 was obtained with an efficiency (?) of 1.05%.