What did we do?

Today we went to the STM, in order to prepare the silicon sample. During the night, the sample was outgassed at 600°C in the preparation chamber and the sample holder too.

We run a current in the sample to heat it at nearly 1000°C. It releases contaminants, evacuated thanks to the pumps. It removes the native oxide around silicon.

The resistivity of the material, which is higher than metal's one, enables us to warm it by direct current. If the sample was a really good conductor, the resistivity wouldn't be enough to warm it. That's why other methods are used, like electronic bombardment for heating metallic samples.

If a material is over around 550°C, it emits light, which color depends on the temperature. In order to measure the temperature, a pyrometer which scans the wavelength emitted is used.

The green pyrometer

 

Then, we prepared the tips for the STM: we had to cut the threads.

 

We also tried to measure the resistivity of a superconductor when it's warm (ambient temperature) and when it's cold (cooled thanks to liquid azote). However, we didn't succeed because of a few problems: it may especially have conductor varnish on the superconductor.

Glued wires

 

We are rather sad but we won't give up! Let's try again!