Interface induced diffusion.

Interface induced diffusion had been identified in a thin film system damaged by electron bombardment. This new phenomenon was observed in Al2O3 (some nm thick)/Si substrate system, which was subjected to low energy (5 keV) electron bombardment producing defects in the Al2O3 layer. The defects produced partially relaxed. The rate of relaxation is, however, was different in the vicinity of the interface and in the "bulk" parts of the Al2O3 layer. This difference creates an oxygen concentration gradient and consequently oxygen diffusion, resulting in an altered layer which grows from the Al2O3/Si substrate interface. The relative rate of the diffusion and relaxation is strongly temperature dependent, resulting in various altered layer compositions, SiO2 (at room temperature), Al2O3 + AlOx + Si (at 500 °C), Al2O3 + Si (at 700 °C), as the temperature during irradiation varies. Utilizing this finding it is possible to produce area selective interface patterning.

Electron irradiation induced amorphous SiO2 formation at metal oxide/Si interface at room temperature; electron beam writing on interfaces.

Al2O3 (5 nm)/Si (bulk) sample was subjected to irradiation of 5 keV electrons at room temperature, in a vacuum chamber (pressure 1 × 10-9 mbar) and formation of amorphous SiO2 around the interface was observed. The oxygen for the silicon dioxide growth was provided by the electron bombardment induced bond breaking in Al2O3 and the subsequent production of neutral and/or charged oxygen. The amorphous SiO2 rich layer has grown into the Al2O3 layer showing that oxygen as well as silicon transport occurred during irradiation at room temperature. We propose that both transports are mediated by local electric field and charged and/or uncharged defects created by the electron irradiation. The direct modification of metal oxide/silicon interface by electron-beam irradiation is a promising method of accomplishing direct write electron-beam lithography at buried interfaces.

Microstructural stability of the Kirkendall plane in solid-state diffusion.

In a diffusion-controlled interaction, the Kirkendall plane, as marked by inert particles placed at the original contact surface of a reaction couple, need not be unique. Multiple planes can develop, and sometimes the Kirkendall plane does not exist at all. A phenomenological approach is introduced to rationalize the Kirkendall-effect-mediated migration of macroscopic inclusions inside a diffusion zone.

[Scanning electron microscopy in the study of surface treatment methods used in the repair of porcelain-fused-to-metal restorations]. / A fémre égetett kerámiapótlás javításánál használatos felszínérdesítési eljárások pásztázó elektronmikroszkópos (SEM) vizsgálata.

According to the literature the ceramic crowns are damaged in 1%-9% of the cases. In order to repair the damage with polimers, first the exposed surfaces have to be made microretentive. Our aim was to investigate with scanning electronmicroscope how the different surface treatment methods modify the structure of metal and ceramic surfaces. We applied two different methods of grinding: 40 microns grained diamond, K1 burs stone (SILISTOR) for ceramic and metal surfaces. The third surface treatment was the application of HF acid for ceramic surface and the sandblasting for metal surface. To achieve microretention the latter mentioned methods increased the most the retentive surface.