大気圧以上の高圧力下でのプラズマＣＶＤによるダイヤモンドの高速形成

Abstract

A new microwave plasma CVD system for generating diamond is developed and the experiments for synthesizing diamond under higher pressure than atmospheric pressure are carried out. Methane concentration in hydrogen carrier gas and substrate temperatures are optimized as the most important experimental conditions for generating diamond using the CVD system. Experiments in which diamond is synthesized under higher pressure than atmospheric pressure are also carried out, and growth rates and Raman spectra are investigated. Consequently, the growth rate of diamond using this CVD system is 100 micrometers thickness per hour, which is ten times higher than when conventional low pressure CVD systems are used. It is found that the optimal methane concentration exists, which becomes higher as pressure increases. From the experimental results obtained under conditions in which the pressure is varied from 800 hPa to 3000 hPa and the other conditions are maintained at the same values, it is also found that the growth rate of diamond reaches a maximum at 1500 hPa. This result shows that optimization of the other conditions is necessary to obtain the highest growth rate of diamond at 3000 hPa.