EFFECT OF MEV ELECTRON-IRRADIATION ON GOLD ATOM IMPLANTATION INTO SILICON-CARBIDE AND SILICON-NITRIDE

Electron-irradiation-induced gold atom implantation into alpha-SiC and beta-Si3N4 has been studied by ultrahigh voltage electron microscopy (UHVEM). Bilayer films of Au(target atom)/alpha-SiC (substrate) and of Au (target atom)/beta-Si3N4 (substrate) were irradiated with 2-MeV el ectrons in a UHVEM with the electron beam incident on the gold layer. In the Au/alpha-SiC system, irradiation with 2-MeV electrons first ind uces amorphization of the alpha-SiC substrate, and then with continued irradiation gold atoms which have been knocked-off from the gold laye r by the collision with 2-MeV electrons are implanted into the amorpho us SiC substrate. The distribution of gold in amorphous SiC is not uni form and there exists a concentration fluctuation of gold with the ave rage wavelength of a few to several nm. In the Au/beta-Si3N4 system, i t seems difficult to implant gold atoms into the beta-Si3N4 substrate by MeV electron irradiation. The ease with which gold implantation int o ceramic substrates takes place has been discussed in terms of the ch emical constraint effect.