Transmission electron microscopy interface imaging

Figure 2.18. Scanning electron microscopy (a) and transmission electron microscopy (b) images of a free-standing mesoporous silica film grown at the air-water interface.

Takeshita, F., Ayukawa, Y, lyama, S., Murai, K., and Suetsugu, T. (1997). Long-term evaluation of bone-titanium interface in rat tibiae using light microscopy, transmission electron microscopy, and image processing. /. Biomed. Mater. Res. 37,235-242. 

Transmission electron microscopy (TEM) is a powerful and mature microstructural characterization technique. The principles and applications of TEM have been described in many books [16 20]. The image formation in TEM is similar to that in optical microscopy, but the resolution of TEM is far superior to that of an optical microscope due to the enormous differences in the wavelengths of the sources used in these two microscopes. Today, most TEMs can be routinely operated at a resolution better than 0.2 nm, which provides the desired microstructural information about ultrathin layers and their interfaces in OLEDs. Electron beams can be focused to nanometer size, so nanochemical analysis of materials can be performed [21]. These unique abilities to provide structural and chemical information down to atomic-nanometer dimensions make it an indispensable technique in OLED development. However, TEM specimens need to be very thin to make them transparent to electrons. This is one of the most formidable obstacles in using TEM in this field. Current versions of OLEDs are composed of hard glass substrates, soft organic materials, and metal layers. Conventional TEM sample preparation techniques are no longer suitable for these samples [22-24], Recently, these difficulties have been overcome by using the advanced dual beam (DB) microscopy technique, which will be discussed later. 

Figure 9.9 Cross-sectional transmission electron microscopy images of two Au/DIP/silicon oxide hetero-structures. While the An contact prepared at (a) -120 °C and a rate of 23 A/min exhibits rather weU-defined interfaces, the An contact prepared at (b) 70 °C and a rate of 0.35 A/min shows strong interdiffusion. Note that individual lattice planes of the DIP film can be resolved. Figures by courtesy of A. Durr and from Ref. [86] with permission.

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