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from the breaking-the-thermionic-limit dept.
Purdue University researchers have demonstrated a transistor using a negative capacitor made with hafnium zirconium oxide:
Researchers have experimentally demonstrated how to harness a property called negative capacitance for a new type of transistor that could reduce power consumption, validating a theory proposed in 2008 by a team at Purdue University.
[...] Capacitance, or the storage of electrical charge, normally has a positive value. However, using the ferroelectric material in a transistor's gate allows for negative capacitance, which could result in far lower power consumption to operate a transistor. Such an innovation could bring more efficient devices that run longer on a battery charge.
[...] Properly switching off [transistors] is of special importance to ensure that no electricity "leaks" through. This switching normally requires a minimum of 60 millivolts for every tenfold increase in current, a requirement called the thermionic limit. However, transistors that harness negative capacitance might break this fundamental limit, switching at far lower voltages and resulting in less power consumption.
Steep-slope hysteresis-free negative capacitance MoS2 transistors (DOI: 10.1038/s41565-017-0010-1) (DX)
2014: Negative capacitance in a ferroelectric capacitor (DOI: 10.1038/nmat4148) (DX)
2008: Use of Negative Capacitance to Provide Voltage Amplification for Low Power Nanoscale Devices (DOI: 10.1021/nl071804g) (DX)
(Score: 2) by c0lo on Thursday December 21 2017, @09:46AM (2 children)
I don't know well how negative capacitance works inside MOSFETs, but I do recall that a positive inductance acts as a negative capacitance. At least in AC.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 5, Informative) by Dr Ippy on Thursday December 21 2017, @02:20PM (1 child)
No. Negative capacitance is not the same as inductance!
Capacitance is governed by the equation i = C dv/dt, and for a negative capacitance C has a minus sign. This means that, as voltage v across the capacitor increases, current i flows out of the capacitance (it would normally flow in). Or, put the other way around, dv/dt = i/C; if you draw current from a negative capacitance (remove charge from it) its voltage increases.
Inductance, on the other hand, is governed by v = L di/dt (or equivalently, di/dt = v/L) which is quite a different kettle of fish.
From a practical viewpoint, if you consider sinusoidal a.c., negative capacitance can cancel positive capacitance at all frequencies, while inductance can cancel capacitance at only one frequency: resonance.
These may seem like abstract theoretical concepts, but if they can be realised they do potentially have practical engineering applications.
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(Score: 2) by Bot on Friday December 22 2017, @01:05AM
> if they can be realised they do potentially have practical engineering applications.
my AI expects realdonaldtrump to praise this tech as being able to prevent the natural flow of immigrants, once adopted in the trump wall.
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