Superconductor-Insulator-Normal Metal (SIN) Tunnel Junction Thermometry (Shadow Evaporation Technology).

Ian Agulo and Leonid Kuzmin

The aim of this project is to fabricate and characterize a thermometer based on superconductor-insulator-normal metal (SIN) tunnel junctions.

The students will first learn to do photolithography and electron-beam lithography. The electron-beam lithography procedure will include all the steps starting from a design or pattern created in a CAD File, and then conversion of this pattern to JEOL format which the e-beam machine can recognize, and then preparation of the sample for exposure (i.e. spinning and baking of the resists) and finally exposure using the e-beam machine.

After the resist has been developed, the sample will be cleaned in a plasma process.

The next step that the students will learn is creation of the SIN tunnel junction structure. This is achieved by the shadow-evaporation technique.

The metals will be thermally evaporated. The first is Al evaporated at and angle of about 50 degrees, and then oxidation of Al (to create the oxide), and finally evaporation of a normal metal (e.g. Cu) at an angle of 0 degrees. A lift-off process will then be done to remove the resists and the unwanted metals.

The final task will be to calibrate and measure the thermometer in a 3He cryofree refrigerator at a temperature of 280 mK.

The results will be summarized for the report and could be presented for publication.

Contact:
Leonid Kuzmin
<leonid.kuzmin -et- mc2.chalmers.se>