Physical and Chemical Mechanisms of Preparation Techniques - Sample Preparation Topic for Transmission Electron Microscopy - page 118

Fig. 5.24 Ion Gun
Evaporator device

Quartz ‡ Monitor

Substrate Holder

Ion Beam

Ion Source

Evaporation
Source

Pumping

Gas Entry

components. The advantage of this technique is that a coating can be made at room
temperature, or any other temperature, if a device is included for heating or cooling
the sample. Therefore, this technique is used to synthesize a multitude of materials;
multilayer structures can be obtained using simultaneous and localized evaporation
of several materials by moving the substrate. Since there is no contact between the
plasma and the growing layer, contamination is minimal. One of the purposes of this
technique is to eliminate the columnar structure of deposits that appears during their
growth. Ion bombardment significantly influences the arrangement of the atoms of
the layer being formed; adherence to the substrate is improved, internal stresses are
reduced, and impurities disappear. The optical characteristics of the layer as well as
its electrical resistance are markedly improved.

Cathodic Pulverization

This system is widely used for scanning electron microscopy. It consists of ejecting
atoms from a metallic cathode using an ionized plasma gas, usually argon, under a
residual vacuum on the order of a few tens of pascals. These ions are deposited “in
a rain” on the specimen placed on the anode.