Improved high quality gate dielectrics and methods of preparing such dielectrics are provided. The upper side and the lower side are thinly coated with a film of metallic Ni-based, Co-based, or Ni\u2014Co-based braze powder with a particle size in the nanometer range, wherein both the braze foil and also the braze powder additionally include grain boundary stabilizing elements as alloying elements. The apparatus also includes a rotating time of flight diffusion module and a non-rotating wall thickness module carried by the inspection unit.