Hydrogen in monocrystalline CVD boron doped diamond

The diffusion properties of hydrogen have been investigated in homoepitaxia l layers of CVD boron doped diamond as a function of the diffusion temperat ure, the boron dopant concentration and the nature of the hydrogen source ( rf or microwave plasma). Preliminary hydrogen effusion experiments on these hydrogenated samples are also reported. For both kinds of plasma we show t hat, below diffusion temperatures of 500 degrees C, the hydrogen diffusion is limited by trapping on boron accepters. The onset of dissociation of B, H pairs occurs at 550 degrees C which implies a significantly higher stabil ity of these pairs in diamond compared to silicon. However, a higher hydrog en diffusion activation energy is found in the microwave plasma exposed sam ples compared with the rf plasma exposed samples together with the absence of the subsurface hydrogen accumulation layer which is observed after rf pl asma. Hydrogen effusion experiments show that in the rf plasma exposed samp les the main effusion peak at 720 degrees C is attributed to the subsurface hydrogen accumulation layer. Another effusion peak at 850 degrees C is asc ribed to the desorption of hydrogen adsorbed at the surface.