Squeezing transistors really hard generates energy savings

December 6, 2013
The electrical current passing through a transistor is conducted by a slice of silicon. In the new transistor, this is sandwiched between layers of piezoelectric material. As this material (shown in red) expands, the silicon (shown in blue) is compressed.

Transistors, the workhorses of the electronics world, are plagued by leakage current. This results in unnecessary energy losses, which is why smartphones and laptops, for example, have to be recharged so often. Tom van Hemert and Ray Hueting of the University of Twente's MESA+ Institute for Nanotechnology have shown that this leakage current can be radically reduced by "squeezing" the transistor with a piezoelectric material (which expands or contracts when an electrical charge is applied to it). Using this approach, they have smashed the theoretical limit for leakage current. Tom van Hemert will defend his PhD dissertation on 6 December.

If silicon is squeezed, this affects the freedom of movement of the electrons in this material. This can promote or restrict the flow of electrical current. Compare it to a garden hose. When you stand on it, less water comes out. But strangely enough, the flow of electrons in silicon actually increases when the material is compressed.

Only pinch when necessary

In modern microchips, every single transistor is continuously exposed to enormous pressures of up to 10,000 atmospheres. This pressure is sealed in during the manufacturing process, by surrounding the transistors with compressive materials. While this boosts the chip's processing speed, the also increases. The use of means that the transistors are only put under pressure when this is necessary. This can generate considerable savings in terms of .

Limit smashed

The underlying concept was originally developed by Ray Hueting. In order to turn this into reality, Tom van Hemert had to find a way of linking theories of mechanical deformation with quantum-mechanical formulas describing the electrical behaviour of transistors. The calculations indicate that "garden hose transistors" are much better than conventional transistors at switching from off to on. According to the classical , a charge of at least 60 millivolts is needed to make a transistor conduct ten times more electricity. The piezoelectric transistor uses just 50 millivolts. As a result, either the leakage current can be reduced, or more current can be carried in the on-state. Either way, this will boost the performance of modern microchips, while - importantly - cutting their energy consumption.

The results of this research were recently published in a leading journal, Transactions on Electron Devices. On 6 December, Tom van Hemert hopes to be awarded a Phd for his dissertation, which is entitled "Tailoring strain in microelectronic devices".

Explore further: Universal transistor serves as a basis to perform any logic function

Related Stories

Taking transistors into a new dimension

March 12, 2013

A new breakthrough could push the limits of the miniaturization of electronic components further than previously thought possible. A team at the Laboratoire d'Analyse et d'Architecture des Systèmes (LAAS) and Institut d'Électronique, ...

Toward tinier transistors

July 3, 2013

(Phys.org) —The foundation of many, many modern electronic devices – including computers, smart phones, and televisions – is the silicon transistor. However, the shrinking of consumer electronics is driving researchers ...

Recommended for you

Facebook ready to test giant drone for Internet service

July 30, 2015

Facebook says it will begin test flights later this year for a solar-powered drone with a wingspan as big as a Boeing 737, in the next stage of its campaign to deliver Internet connectivity to remote parts of the world.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

MR166
1 / 5 (11) Dec 07, 2013
I always thought that most of the losses in CMOS semiconductors were due to junction capacitance and switching losses. Leakage is a very small part of the equation. What are the losses associated with turning this piezoelectric junction on and off?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.