Correlated oxides set to challenge silicon’s dominance
1 min read
A laboratory which usually studies fuel cells has developed a correlated oxide which is said to have a reversible change in resistance of eight orders of magnitude and the potential to replace silicon.
The research, conducted by Professor Shriram Ramanathan at Harvard's School of Engineering and Applied Sciences, has drawn on experience with thin films and ionic transport. According to the team, the work establishes correlated oxides as promising contenders for use in future 3D circuits, as well as in adaptive photonic devices.
Silicon transistors are hard to beat, the team admits, pointing to the need for an on/off ratio of at least 104 for practical use. "It's a pretty high bar to cross," said Prof Ramanathan. His team has, however, made a transistor from samarium nickelate that achieves an on/off ratio of more than 105.
Samarium nickelate and other correlated oxides are quantum materials.
"In a traditional material, if you have two electrons in adjacent orbitals, and the orbitals are not completely filled, the electrons can move from one orbital to another. But in correlated oxides, the electrons repulse each other so much that they cannot move," said Prof Ramanathan. "The occupancy of the orbitals and the ability of electrons to move in the crystal are tied together closely – or 'correlated'. Fundamentally, that's what dictates whether the material behaves as an insulator or a metal."
In future work, the researchers will investigate the device's switching dynamics and power dissipation.
