Hydrogen isotope tracer experiment in a-C:H film deposition: Reactive RF magnetron sputtering with CH4 and D2

Hydrogen isotope tracer experiment is taken on the a-C:H + D films prepared by the reactive RF magnetron sputtering including CH4 and D2. The nine different samples were prepared with changing the partial pressure of D2 in the process gas. The concentrations of H and D relative to C in the films were determined by ERDA and RBS. It was found that the total amount of H + D concentration is constant at ~ 22.7%. This means that hydrogen makes a chemical bond with one of four hands of C, and little amount of H atoms exist in the interstitial site. The D concentration in the films linearly increases with increasing the relative partial pressure PD2/(PD2 + PCH4). This implies that the activated CH4 and D2 molecules stick to the growing films and release the H and D atoms. XPS results show that all the prepared samples have the same sp3-rich structure.

► We used D2 and CH4 in the process gases to deposit a-C:H films. ► H and D concentrations were determined by ion beam analysis. ► H and D concentrations in the films are completely in proportion of the abundance ratio of molecules.