Diffusion of deuterium in diamond-like carbon films was studied (figure 6). The deuterium concentration profiles in D+-ion-implanted films were measured by secondary-ion mass spectrometry. A model was proposed to describe the experimental depth profiles. In this model it was assumed that atomic D was the diffusing species, whereas D in clusters was immobile. The results showed that the concentration of D clusters relative to the total D concentration increased when the total D concentration decreased, leading to a concentration-dependent diffusion. The diffusion coefficients obtained for atomic D resulted in an activation energy of 2.9eV. The solid solubility of D was observed to decrease with increasing temperature.

Concentration-Dependent Deuterium Diffusion in Diamondlike Carbon Films. Ahlgren, T., Vainonen, E., Likonen, J., Keinonen, J.: Physical Review B, 1998, 57[16], 9723-6

Figure 6

Diffusion of D in diamond film

Figure 7

Diffusion of D in diamond film

Black circles: 0at%Si, black squares: 6at%Si,

 white circles: 15at%Si, white squares: 33at%Si