‘Negative capacitance’ could Bring more Efficient Transistors

Purdue University

March, 2018
‘Negative capacitance’ could Bring more Efficient Transistors
A new type of transistor (a) harnesses a property called negative capacitance. The device structure is shown with a transmission electron microscopy image (b) and in a detailed “energy dispersive X-ray spectrometry” mapping (c). (Purdue University photo/Mengwei Si)

Researchers at Purdue University’s School of Electrical and Computer Engineering have experimentally demonstrated how to harness a property called negative capacitance for a new type of transistor that could reduce power consumption. This experimentation has validated a theory proposed in 2008 by a team at Purdue.

The researchers used an extremely thin—or 2-D—layer of the semiconductor molybdenum disulfide to make a channel adjacent to a critical part of transistors called the gate. Then they used a ferroelectric material called hafnium zirconium oxide to create a key component in the newly designed gate called a negative capacitor.

The original theory for the concept was proposed in 2008 by Supriyo Datta, the Thomas Duncan Distinguished Professor of Electrical and Computer Engineering, and Sayeef Salahuddin, who was a Purdue doctoral student at the time and is now a professor of Electrical Engineering and Computer Sciences at the University of California, Berkeley.

New findings demonstrate the ferroelectric material and negative capacitance in the gate results in good switching in both the on and off states. The negative capacitance was created with a process called atomic layer deposition, which is commonly used in industry, making the approach potentially practical for manufacturing. The research is ongoing, and future work will explore whether the devices switch on and off fast enough to be practical for ultra-high speed commercial applications.

Click here to more about this project.

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