HOME
about MPG Contact Events Job Offers Links Index Certificate Imprint DEUTSCH
Zurück zur Startseite
Luftbild_Institut  
Research
Publications
The Institute
News
Service
[Intranet]
StEM
Facilities
Sample Preparation
Facilities
  Instrumentation     Sample Preparation     Software  

The material to be analyzed in the transmission electron microscope must be electron transparent in the area of interest.
For this purpose we use various techniques for the preparation of different materials (metal, ceramics, semiconductors and also combinations of these materials). In a first step the material is machined into an adequate external shape by mechanical preparation, e.g. stamping, ultrasonic drilling, diamond-wiresawing and disc-sawing. The external diameter of the material must not exceed 3 mm.
The preparation of cross-sections of interfaces mostly requires the production of a sandwich made of layer/substrate-plates which are glued into a ceramic or metal tube which provides the mechanical stability. After sawing the micro-tube into disks, the disks are mechanically thinned to a thickness of 100 to 150 µm. Frequently further material is removed from the center of the disk using a dimpler until a thickness of 10 to 50 µm is reached. The final thickness depends on the stability of the sample. Final thinning to electron transparency is done by ion sputtering with high-energetic Ar+ ions.
Different ion-thinning devices are available which permit adapting the sputtering parameters to the requirements of the sample. These parameters include the voltage (100 V – 6 kV), the angle of ion incidence (3° – 30°), and the direction of ion incidence (e.g. sectional thinning mode). Furthermore, there is the possibility to cool the sample with liquid nitrogen during ion thinning. Light-optical microscopes equipped with CCD cameras are attached to the ion-thinning devices to control the thinning process in situ.
Metal samples are frequently prepared by electropolishing (Tenupol, Struers).
Electron transparency can also be achieved by pure mechanical thinning. For this purpose a tripod-polisher (South Bay Technology, Allied TechPrep) or ultra-microtome cutting is used.
fter the preparation TEM-samples can be coated with carbon in order to avoid charging of the sample in the electron microscope.
A Fischione plasma cleaner is used for removing hydrocarbon contamination of specimens before insertion into the TEM.


drucken Print version topPfeil  Top
© 2012, Max Planck Institute for Metals Research, Stuttgart