Single-electron transistors: Light at the end of the tunnel

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Electronics are expected to get—and have to get—increasingly smaller and more efficient. Of course, at some point that is when quantum electronics gets in the way. A European research project is making a virtue of necessity and using the “unpleasant” effects to implement a new transistor concept.

In four years, Intel’s first microprocessor will celebrate its fiftieth birthday. At the time, the 4004 had 2,300 transistors on a single chip, which was a sensation. To get any attention today, it would have to have trillions. For that kind of density, the transistors’ structure sizes had to shrink from the width of a hair (70,000 nm) to 14 nm during the same period. And there is no end in sight.

According to experts, current manufacturing techniques are expected to reach the end of the line between 2025 and 2035. Then transistors with completely new designs and even smaller structures will be needed. But then quantum effects would not only influence the components’ physical properties, they would dominate them. So scientists involved in the European research project titled “Single Nanometer Manufacturing for beyond CMOS Devices” (SNM)  have made a virtue of necessity and exploited it for their own ends. The result: Ultra-small single-electron transistors (SETs) that switch using just one electron and have functional structures of less than two nanometers. They could solve the problem of miniaturization and power consumption in future electronic chips.

Until now, operating tiny transistors of this type was only possible in the laboratory at extremely low temperatures below minus 200°C. SNM transistors operate at normal ambient temperatures and can be manufactured in batches.

Single-electron transistors for quantum computers

Until this type of ultra-small circuit can be produced, the individual, incredibly complex steps must be carried out dozens if not hundreds of times. With the help of so-called slow electrons, scientists at TU Ilmenau formed structures below ten nanometers in size using one or multiple nano-sized needles. This inscribing process, known as scanning-probe technology, not only makes it possible to pattern nano-structures, but to read and arrange them with extreme precision. That opens the door to the future world of quantum computing.


About the project

The 18-million-euro project titledSingle Nanometer Manufacturing for beyond CMOS Devices (SNM)” ( involves 16 research partners from science and industry led by Professor Ivo W. Rangelow, Head of the Micro- and Nano-electronics Systems Department at TU Ilmenau.


Knowledge Base

TU Ilmenau: Single Nanometer Manufacturing for beyond CMOS devices (PDF)


Single-electron transistors (Image: TU Ilmenau)

In the future, transistors will have electronic structures of less than two nanometers. (Image: TU Ilmenau).