ALUMINUM NITRIDE BUFFER LAYER FOR DIAMOND FILM GROWTH

The role of aluminum nitride (AlN) as a buffer layer on the nucleation and growth of diamond on silicon and steel substrates during hot fila ment chemical vapor deposition (HF-CVD) has been investigated systemat ically. The scanning Auger electron microscopy (AES) is employed to st udy chemistry and content of carbon on the surface and in subsurface r egions of AlN as a function of HF-CVD parameters. It is found that AlN offers an excellent diffusion barrier fur carbon over a wide range of temperature and hydrocarbon content of CVD gas environment, with simu ltaneous inhibition of graphitization. It also facilitates nucleation of diamond phase. The surface reactions between AlN and carbon are dis cussed in terms of hydrogen-assisted phase transformations. We have de veloped a two-step procedure to obtain a continuous diamond film on st eel substrates. The characteristic features of AlN have been exploited to obtain adherent and graphite-foe diamond deposits on various types of steels, including low carbon steel, tool steel, high speed steel, and bearing steel.