STUDY OF CARBON NANOTUBE GROWTH BY METHOD OF HWC IN PLASMA-VHF-PECVD AT LOW TEMPERATURES FOR SOLAR CELL DEVICE APPLICATIONS

• Main Author: Abidin, Kurniati
• Format: Dissertations
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/62281
• Institution: Institut Teknologi Bandung

The use of Carbon Nanotube (CNT) in photovoltaic has a significant impact in the commercial solar cell market. The uniqueness of its optical and electronic properties leads CNT to be applied to various active layers of solar cells, while the high conductivity and transmittance of this material make it applicable as transparent electrodes. The type and quality of the CNT formed is determined by the catalyst, deposition method and parameter. Plasma Enhanced Chemical Vapor Deposition (PECVD) is a CNT deposition method that operates at low temperatures, which is an efficient way especially if employed on an industrial scale. Besides this efficiency, the process is easy to operate, so PECVD method is widely used and continues to be developed. One of the developments is HWC in plasma-VHF-PECVD. The addition of hot wire in plasma helps disperse the gas source when it is in the electrode area, while the use of high rf frequencies allows for lower power consumption. CNT deposition using PECVD method requires a catalyst in the growing process, which is necessary to decompose carbon sources and as a guide for CNT growth. Catalyst deposition has been carried out through a vacuum thermal evaporation technique, which is a common method of physical vapor deposition (PVD). By optimizing the Ag source mass parameter, deposition time, annealing time and temperature, the catalyst with a size of 35.82 nm has been obtained. Parameter optimization in the deposition process of HWC in plasma-VHF-PECVD has also been undertaken, including optimization of CH4 flow rate, substrate temperature and hot wire power supply voltage. Through this optimization, the best semiconductor CNT has been gained at a substrate temperature of 275oC, a flow rate of 50 sccm and a power hot wire voltage of 4V. Its diameter is 56 nm, with the IG/ID of 1.114 and the band gap of 3.14 eV. Moreover, the optimization has resulted in a conductor CNT with a band gap of 0.5 eV, at a flow rate of 50 sccm, a substrate temperature of 275oC and a hot wire voltage of 2.6 V. The IG/ID ratio is 1.079, while the band gap is 0.5 eV.