High-transparency Schottky contacts in a silicon Josephson field-effect transistor, TransJoFET

Important results from the project

We have successfully manufactured working silicon-JoFETs and demonstrated control of the Schottky barrier height. However, further measurements are required to complete the device characterization at mK temperatures. Other important results include a couple of patentable ideas. They concern device structures for mitigating external noise as well as device structures along with their manufacturing processes for large-scale integration of millions of qubits.

Expected long term effects

For the long-term perspective, however still within the 10-year, our silicon JoFET technology is expected to lead to QC chips that in principle can integrate millions of qubits. The chip size will be reasonable and comparable with today’s CPU chips typically of a couple of centimeters in side length. Millions or even billions of qubits per chip are necessary for meaningful quantum computing for societal needs including drug discovery.

Approach and implementation

The project went slower than planned because of malfunctioning tools and processes in both Ångström and Electrum cleanrooms, which led to an approved delay of the closure of the project by 4 months. Besides, the mK-characterizations became more comprehensive and took much longer time. Despite of all these setbacks, the project execution and the project design have gone well with fabrication of well-functioning Si JoFETs, by drawing on our knowledge in CMOS technology and ”dopant segregation”.