Diffusion etching

Also visible in Fig.2(a) are diffusely etched bands coincident with and extending beyond the rays containing the slip bands. This etching effect represents a type of kink band (20), i. e., an area at die edges of which the orientation changes abruptly. Similar kink bands have also been observed in abraded surfaces of zinc (37), and can be expected to be general. 

A micropump driven by piezoelectrics was developed at the Technical University of Ilmenau. The privileged direction of flow is determined by two pyramid-shaped diffusers etched into silicon (Fig. 6.119). Due to their geometry, these diffusers exhibit different flow resistances for each direction at higher flow speeds (Reynolds number > 100). This characteristic enables alternating flows to be rectified through a two paces forward, one pace back principle. With valve channel widths between 80 pm and 300 pm depending... 

The vacancy is very mobile in many semiconductors. In Si, its activation energy for diffusion ranges from 0.18 to 0.45 eV depending on its charge state, that is, on the position of the Fenni level. Wlrile the equilibrium concentration of vacancies is rather low, many processing steps inject vacancies into the bulk ion implantation, electron irradiation, etching, the deposition of some thin films on the surface, such as Al contacts or nitride layers etc. Such non-equilibrium situations can greatly affect the mobility of impurities as vacancies flood the sample and trap interstitials. 

Fig. 12. Auger electron spectroscopy (AES) sputter-depth profile of CAA-treated titanium after various exposure.s in vacuum (a) as anodized, (b) 450°C for 1 h, and (c) 7(X)°C for 1 h. The sputter etch rate is 1.5 nm/min. The line indicates the original interface. The arrow denotes oxygen diffused into the substrate. Adapted from Ref. [51].

As corrosion products develop, so the rate of 02 diffusion reduces and the rate of general etch corrosion slows down. But in practice, the presence of surface deposits tends to promote various forms of localized corrosion such as tuberculation, pitting corrosion, and stress corrosion, and consequently the rate of corrosion continues unabated. 

A SiC buffer layer was grown on a silicon wafer at 1150-1300°C from one to 45 minutes using C3Hg and H2 as reactant gases. The thickness of the film increased gradually by diffusion of Si into the deposit until a thickness controlled by temperature and silicon etching was reached. 

Type of adhesion diffusion ion etching metallic bond... 

The micro structured platelets, hold in a non-conducting housing, were realized by etching of metal foils and laser cutting techniques [69]. Owing to the small Nemst diffusion layer thickness, fast mass transfer between the electrodes is achievable. The electrode surface area normalized by cell volume amounts to 40 000 m m". This value clearly exceeds the specific surface areas of conventional mono- and bipolar cells of 10-100 m m. ... 

The slit is made by pEDM the micro channels are etched in the plate [1-3]. The gas chamber and the two diffusers are made by pEDM. The heat exchange channels are manufactured by micro milling. 

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