Effects of H_2 gas addition into process and H ion implantation on the microstructure of hydrogenated amorphous carbon films prepared by bipolar-type plasma based ion implantation

摘要

Hydrogenated amorphous carbon films are deposited on Si(l 00) and SiO_2 glass substrates by a bipolar-type plasma based ion implantation system. The films are prepared using toluene gas at a constant flow rate of 2 seem. The effects of H_2 gas addition during deposition on the microstructure of the films are examined by electrical conductivity measurements, Raman spectroscopy, elastic recoil detection analysis (ERDA) and optical spectroscopy. In addition, H implantation is also carried out using H_2 plasma discharge. Thickness of the films is approximately 60 nm for all samples. It is found that electrical conductivity slightly increases with increasing additive H_2 flow rate. However, the conductivity drastically decreases after H implantation. Raman analysis reveals that H_2 gas addition slightly causes the film graphitization, but the H implantation does it amorphization. The results of ERDA show that the H concentration in the films slightly decreases with increasing H_2 gas addition, but increases by H implantation. In spite of H_2 gas addition, the optical band gap is not changed and kept approximately 0.7 eV. However, H implantation makes it increase up to approximately 1.0 eV.