Understanding About Scanning Electron Microscopy (sem)

Not far from the birth of TEM, SEM was first developed in 1938 by means of Manfred von Ardenne (Germany scientists). The basic concept of SEM was actually delivered by Optimum Knoll (inventor TEM) during 1935. SEM worked depending on the principle of electron beam scans over the sample surface, and than the information that was received was subsequently changed to your images.

The way to make the image formation within the SEM was different from what happened to the optical microscope and TEM. In SEM, the image was made based on the detection of new electrons (secondary electrons) or simply the reflected electrons emerging within the sample surface when the sample surface was scanned through an electron beam.



After the secondary electrons or resembled electrons were detected further more, the signal was strengthened and then the amplitude was displayed during the dark-light shades on all the CRT (cathode ray tube) display screen. In the CRT computer screen, a picture of object structure that had been enlarged could be personally seen. In the process with operation, the SEM did not require the sample which had been thinned, so that how to attract used to view objects from the perspective of three measurements.

Thus, the SEM had excessive and familiar resolution to observe nano-meter sized objects. Nevertheless, high resolution was obtained for scanning during the horizontal direction, while the vertical scan had very low resolution. This was a weakness of SEM this had no solution.

However, since around the 1970s, a new microscope has been formulated. This new microscope had a high resolution both horizontally plus vertically, which was also known as "scanning probe microscopy (SPM). " SPM had a working principle that was different from SEM and TEM. It was a new generation of this type of scanning microscope.

Microscopes that are now known to have this kind are scanning tunneling microscope (STM), atomic force microscope (AFM) and scanning near-field optical microscope (SNOM). This type of microscope is widely used in nanotechnology research.