contact*

The global need for fast, small and precise electronic devices has seen a surge in the last few decades due to the rapid growth in demand of consumer electronics but also on the forefront of fundamental scientific analysis.

SrTiO₃ has gained a lot of attention in device development in recent years due to exhibiting a plethora of phenomena ranging from superconductivity(1), an extremely high dielectric constant at low temperature and coupling of ferroelectricity and magnetism (2), with its high dielectric constant making it an ideal platform for magnetoresistive sensors. However, to dip into the world of its phenomena and use STO to its full potential, devices with defined electrical contacts must be fabricated.

An established method to contact STO is by depositing Cr, however, this is far from optimal as Cr develops its own magnetic phase at low temperature (3). Additionally, Cr contacts reach resistivities as low as 10^-5 Ωcm² which is sufficient for mesoscale material characterization but lacks potential as devices become smaller and faster.

In this project we have contacted La-doped STO films grown by MBE at various doping densities with eight different metals and analyzed their contact resistance behavior after annealing in inert atmosphere at medium to high temperatures.

Preliminary results showed that there is a large variety of unconventional metal options available with an ohmic contact to STO, and that thermal annealing can be used as an excellent, simple lever to tune thin-film oxide electrical properties. This presentation will highlight the current ongoing process of La-STO thin-film synthesis optimization and the hunt for the ideal metal-SrTiO₃ contact.

(1) Thaís V. Trevisan, Michael Schütt, and Rafael M. Fernandes Phys. Rev. Lett. 121, 127002

(2) Bréhin, Julien & Chen, Yu & D'Antuono, Maria & Varotto, Sara & Stornaiuolo, Daniela & Piamonteze, Cinthia & Varignon, Julien & Salluzzo, M. & Bibes, Manuel. (2023). Coexistence and coupling of ferroelectricity and magnetism in an oxide two-dimensional electron gas. Nature Physics. 19. 1-7. 10.1038/s41567-023-01983-y.

(3) Hartmut Zabel 1999 J. Phys.: Condens. Matter 11 9303