4W-CryoVac/English
Device: 4W-CryoVac
Responsible person: Joel Joseph
Location: B301, R212
Brief description
Vacuum equipment for measuring resistance as a function of temperature. More precisely: The sample is contacted by means of special measuring heads. The measuring heads each consist of four tensioned copper rods (4-point measurement), whose diameter as well as distance varies from head to head in order to cover different sample geometries, see figure. Temperatures <-150°C are possible by active cooling with liquid nitrogen, which is conveyed through the system by means of a pump; the maximum temperature is about +300°C.
Measurement
The ceramic on which the sample is placed is coated with thermal conductivity gel beforehand and contacted with the appropriate measuring head. (At this point it is advisable to check the contacting of the outer as well as the inner contacts). After closing the system and starting the vacuum pump, the nitrogen can be connected and the nitrogen pump started. The nitrogen pump valve and the heating power are controlled automatically by the settings in the program.
Limitations
Contact difficulties with very thin samples (<500nm layer thickness). In this case, soldered connectors are used, which are connected to the surface by wire bonding.
