Defects in diamond thin films

Defects in diamond films, produced by the filament-assisted chemical-vapor deposition of methane and hydrogen as a function of total gas pressure and substrate temperature, were investigated by electron-paramagnetic-resonance measurements. We found an isotropic g value (2.0028±{}0.0002) independent of growth conditions. The peak-to-peak linewidth increases with pressure from 3.5 to 5 G and the spin density decreases with increasing pressure and temperature and varies between 10¹⁹ and 10¹⁷ spins/cm³. The line shape was found to be the superposition of two components, a narrower Lorentzian and a broader Gaussian, suggesting exchange narrowing and a nonuniform distribution of paramagnetic defects. The line shape was analyzed using Van Vleck's theory of moments and a model regarding the distribution of the dominant paramagnetic center in diamond films was proposed and compared with structural studies on the same films. The temperature dependence of the spin-lattice relaxation rate, evaluated by the saturation method, was also investigated.