System Bits: Sept. 23

Harvard researchers propose correlated oxide as a promising semiconductor for future 3D ICs; researchers at the University of Illinois at Chicago have created a way to create a highly sensitive chemical sensor based on the crystalline flaws in graphene sheets.

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Contender emerges for 3D IC semiconductor material
While silicon has few serious competitors as the material of choice in the electronics industry, transistors cannot keep shrinking to meet the needs of next-gen devices given the significant physical limitations of energy consumption and heat dissipation. To address this, researchers at Harvard University have achieved a reversible change in electrical resistance of eight orders of magnitude using a quantum material called correlated oxide. Essentially, the material has been engineered to perform comparably with the best silicon switches.

This is a new type of correlated transistor where the transistor action is gated by an ionic field. (Source: Harvard University)

This is a new type of correlated transistor where the transistor action is gated by an ionic field.
(Source: Harvard University)

Interestingly, the finding arose in a laboratory usually devoted to studying fuel cells, and the researchers’ familiarity with thin films and ionic transport enabled them to exploit chemistry to achieve the dramatic result. And because the correlated oxides can function equally well at room temperature or a few hundred degrees above it, it would be easy to integrate them into existing electronic devices and fabrication methods, they asserted.. The discovery firmly establishes correlated oxides as promising semiconductors for future 3D ICs as well as for adaptive, tunable photonic devices.

The key to hypersensitive ‘electronic nose’
Researchers at the University of Illinois at Chicago have created a way to create a highly sensitive chemical sensor based on the crystalline flaws in graphene sheets, which have unique electronic properties that were exploited to increase sensitivity to absorbed gas molecules by 300 times.

Grain boundaries are considered faults in many applications because they scatter electrons and may weaken the lattice but the researchers have shown that these imperfections are important to the working of graphene-based gas sensors. As such, the team has created a micron-sized, individual graphene grain boundary in order to probe its electronic properties and study its role in gas sensing.

The grain boundaries can be synthesized on a micrometer scale in a controlled way in order to easily fabricate chip-scale sensor arrays for real-world use such as an electronic nose.