The diffusion and out-diffusion properties of hydrogen were investigated in homo-epitaxial layers of CVD boron-doped diamond which were exposed to a deuterium microwave plasma (figure 8). The diffusion experiments showed that the onset of (B,H) pair dissociation occurred at 550C. The hydrogen diffusion activation energy was 1.4eV. Hydrogen out-diffused at 880C and the diamond surface barrier limited the out-diffusion process. In RF plasma-exposed diamond epilayers, the hydrogen out-diffusion spectra were composed of a peak at 720C related to the sub-surface hydrogen accumulation layer and another one at 840C, attributed to the hydrogen adsorbed at the surface.

Diffusion and Thermal Stability of Hydrogen in Homoepitaxial CVD Diamond Films. Ballutaud, D., Jomard, F., Le Duigou, J., Theys, B., Chevallier, J., Deneuville, A., Pruvost, F.: Diamond and Related Materials, 2000, 9[3], 1171-4

Figure 8

Diffusivity of B in diamond