Self-diffusion studies of 15N in amorphous Si3BC4.3N2 ceramics with ion implantation and secondary ion mass spectrometry

Nitrogen self-diffusion studies in amorphous precursor-derived Si3BC4.3N2 ceramics were carried out, using ion implanted stable N-15 isotopes as tracers and secondary ion mass spectrometry for depth profiling. The analysis of the diffusion profiles in the range of 1500-1700 degrees C did not show the typical Gaussian broadening of the implantation profiles. Instead, we observed the occurrence of a high concentration region where the width of the implantation profile is nearly unchanged due to implantation damage, and a low concentration region where diffusion occurs. The experimentally determined diffusivities obey an Arrhenius behavior with an activation enthalpy of about H=7 eV and a pre-exponential factor D-0 in the order of 5 m(2)/s which indicates a diffusion mechanism via vacancy-like defects. (C) 2000 American Institute of Physics. [S0021- 8979(00)05116-1].