Structural and valence electronic analysis of electron-irradiation-induced foreign-atom implantation by a combination of UHVEM and AES

Abstract

Bilayer films of Pt or Au (target atoms) / α-SiC (substrate) were irradiated with 2 MeV electrons in an ultrahigh-voltage electron microscope, with the electron beam incident on the metal layer. By irradiation, noble-metal atoms were implanted into the SiC substrate. Changes in the microstructures and valence electronic state associated with the implantation were studied by a combination of ultrahigh-voltage electron microscopy and Auger valence electron spectroscopy. The results obtained can be summarized as follows. (1) Irradiation with 2 MeV electrons first induces a crystalline-to-amorphous transition in α-SiC. (2) The noble-metal atoms which have been knocked-off from the metal layer by the elastic collision with the 2 MeV electrons are implanted into the resultant a-SiC (3) The implanted metal atoms make preferential bonding with silicon atoms having dangling bonds. Interaction with carbon atoms may also be present in the Pt/SiC system. (4) During continued irradiation, the metal atoms repeat knocking-off along the beam direction and subsequent bonding with the dangling bonds. The repetition of knocking-off and subsequent bonding is essential to the deep implantation of noble-metal atoms into the SiC substrate.