Characteristics of Diamond-like Carbon Thin Films

다이아몬드성 탄소 박막의 특성

The a-C : H films have been grown on the glass substrate by PECVD method, where plasma was generated with a 60 Hz line power source. The growth rate of films is found to be dependent of the partial pressure of $C_2H_2$. This growth rate is a little higher than that in which $CH_4$ instead of $C_2H_2$ is used. The transmittance is also much higher(95%). The optical energy gap of films is in the range of 1.4~1.8eV depending on the partial pressure of $C_2H_2$. However, this energy gap, which is 1.8eV, is found to be independent of the partial pressure of $C_2H_2$ for the thick films above $2000{\AA}$. The carbonization is checked from peak intensities of D ($sp^3$) and G($sp^2$) peaks in Roman spectra. The hydronization and C-H bonding status in films can also be determined from FTIR results. Both the bonding strength of C-H and the ratio of $sp^3$ to $sp^2$ in bonding are found to be slightly dependent of partial pressure of $C_2H_2$. Judging from above results, we can conclude that the best value for partial pressure of $C_2H_2$ in growing process of thick films is about 13.8%.

수소화된 비정질 탄소 박막은 PECVD 방법으로 제작하였으며 박막의 증착률은 아세틸렌 가스의 함량에 의존하였다. 이것은 메탄 기체를 사용하였을 때와 비교해 조금 높았다. 박막의 광학적 밴드 갭은 1.4~1.8eV였으며 아세틸렌 함량에 밀접한 연관성을 보여주었다. Raman과 FTIR 분광에 의하여 $sp^3/sp^2$의 정성적인 분율을 결정할 수 있었으며 이러한 결과로부터 아세틸렌 함량 13.8%의 박막이 최적의 조건이었다.