Spectroscopic visualization of CH in methane/hydrogen plasmas for synthesis of carbonaceous materials and surface micromorphology

2D spectroscopic observation on effect of nitrogen species on CH abundance and morphology of carbonaceous film by plasma-enhanced CVD

“…Some other lines arising from excited CH, H 2 and atomic hydrogen which have previously been reported [13] can also be confirmed here. However, their intensities are relatively weak compared to those due to nitrogen ones even in the CH 4 rich plasmas.…”

“…However, their intensities are relatively weak compared to those due to nitrogen ones even in the CH 4 rich plasmas. The line from CH at 390 nm is almost obscured by those from nitrogen though CH is the important specie for us to elucidate the plasmas in our study [13]. In this present study, therefore, the line at 430 nm was used for two-dimensional distribution of CH in the plasmas.…”

“…Our previous work showed that the density of CH in the plasma directly affected the morphology of the resultant films and that a bias voltage contributed to prepare higher density electrode materials by PECVD process [13]. In the present work, an attempt to establish a more efficient method to prepare compact carbonaceous electrode materials was made by using N 2 as CH radical-generating accelerant in the methane PECVD.…”

“…The detail of optical instruments used for monitoring synthesis of the carbonaceous films with the radio frequency PECVD (rf-PECVD) has been reported in our previous article [13]. A mixture gas of CH 4 as the carbon source, N 2 as the reaction gas newly added and Ar as the plasma supporting gas was introduced to a vacuum chamber through a rectifier after being pre-mixed.…”

“…In-situ spectroscopic visualization of chemical species in the plasma was made with methane as carbon source gas as in the previous work, where hydrogen was used as a reaction control gas [13]. But in this work, nitrogen replaced hydrogen for its much higher ionization efficiency [14] by which to enrich the spatial density of CH in the plasmas.…”