In modern electronics, silicon is the fundamental thing, silicon transistors are responsible in switching signals and amplification in devices ranging from smartphones to automobiles. But , silicon semiconductor technology faces a fundamental physical problem , it does not allow transistors from operating below a certain voltage. This problem is also called as BOLTZMANN TYRANNY. This limitation disturbs the energy efficiency of computers and other electronics, it poses a significant challenge in the era of artificial intelligence where the rapid calculation is a much needed thing.
MIT researchers have developed an innovative 3D transistor using a novel combination of ultrathin semiconductor materials to overcome this barrier. These devices feature vertical nanowires only a few nano meters wide and achieve performance comparable to cutting-edge silicon transistors even they are operated at much lower voltages, therefore energy efficiency is improved.
“This technology has the potential to replace silicon, maintaining all its functionalities but delivering superior energy efficiency,” says Yanjie Shao, an MIT postdoc and the lead author of a study detailing this advancement.
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Researchers have developed 3D transistors that uses quantum mechanical properties to achieve a good balance of low-voltage operation and high performance. These transistors are very compact, which allows a greater number of chips to be integrated onto a single computer chip.
“With conventional physics, there is only so far you can go. Yanjie’s work demonstrates that we can surpass those limits by exploring new physical principles. While there are still many problems to commercialize this approach, the concept itself is truly revolutionary,” explains Jesús del Alamo, the Donner Professor of Engineering in MIT’s Department of Electrical Engineering and Computer Science (EECS).
The research team includes:
- Ju Li, the Tokyo Electric Power Company Professor in Nuclear Engineering and Materials Science at MIT.
- Hao Tang, an EECS graduate student.
- Baoming Wang, a postdoctoral researcher at MIT.
- Marco Pala and David Esseni, professors from the University of Udine in Italy.
Their study is a major milestone in transistor technology , and it was published in the prestigious journal Nature Electronics.
Quantum tunnelling allows electrons to penetrate energy barriers rather than surmounting them. This effect was basically used to create tunnelling transistors, which encourage electrons to bypass the energy barrier altogether. By leveraging this property, the researchers developed that the devices are now capable of achieving extremely steep switching slopes.
“Now, you can turn the device on and off very easily,” explains Shao.
Even after this remarkable efficiency, tunnelling transistors often operate at low currents, which limits their performance in high-demand applications. If we want to use them in powerful electronic systems, higher current levels are essential to create good transistor switches capable of meeting the demands of era .
Fine-Grained Fabrication: A Leap in Nanotechnology At MIT.nano, MIT’s premier hub for nanoscale research, They developed vertical nanowire heterostructures with a diameter of just 6 nanometers, making them some of the smallest 3D transistors .This precision allowed the team to achieve both sharp switching slopes and high current simultaneously, a breakthrough enabled by a quantum phenomenon known as quantum confinement.
Advancing Beyond Silicon: A Quantum Leap in Transistor Design
We know that traditional silicon transistors function as switches by the flow of electrons across an energy barrier. When a voltage is applied the electrons traverse this barrier, the transistor interchanges between “off” and “on” states. The transistor uses binary digits 0 and 1 which form the foundation of computation in electronic devices.
The efficiency of this process is measured by a parameter known as the switching slope, which measures the sharpness of the transition from “off” to “on.” A steeper switching slope implies that the transistor can switch states at a lower voltage, which leads to enhanced energy efficiency. However, a fundamental physical limitation, known as Boltzmann tyranny which says that a minimum voltage required to switch silicon transistors at room temperature, due to the thermal dynamics controlling electron movement over energy barriers.
To surpass these limitations , the researchers at MIT used novel semiconductor materials — gallium antimonide and indium arsenide — and applied a quantum mechanical phenomenon: quantum tunnelling .
Quantum confinement happens when electrons are confined to a tiny space, changing their mass and properties. This increases the tunneling effect, helping electrons pass through barriers more easily. A small transistor was created , thus the tunnelling barrier became very thin .
“We have a lot of flexibility to design these material heterostructures so we can achieve a very thin tunneling barrier, which enables us to get very high current,” explains Shao.
Overcoming Challenges in Nanometer-Scale Fabrication
It requires high precision to create devices that work on single nanometer . “We are really into single-nanometer dimensions with this work. Very few groups worldwide can fabricate high-performance transistors at this scale. Yanjie is extraordinarily skilled at crafting such well-functioning devices,” notes Jesús del Alamo, the Donner Professor of Engineering at MIT.
After testing it was found that the transistors showed a sharper switching slope than the fundamental limit of silicon-based devices. It is working 20 times better than that of conventional transistors.
“This is the first time we have been able to achieve such sharp switching steepness with this design,” adds Shao.
Towards Greater Uniformity and Novel Designs
We are working to improve the fabrication to get uniformity across the chip. It is pretty obvious that 1 nano meter can also affect the performance at significant level . The Researchers are also working on alternative methods like “VERTICAL FIN-SHAPED STRUCTURES” to improve consistency .
“This work definitively moves in the right direction, delivering significant improvements in broken-gap tunnel field-effect transistor (TFET) performance,” says Aryan Afzalian, a principal technical staff member at imec, a leading nanoelectronics research institute.
“It shows steep switching slopes alongside record drive-current, emphasizing the importance of precise dimensions, extreme confinement, and low-defectivity materials and interfaces achieved through a highly controlled fabrication process.”
*INTEL CORPORATION HAS PARTIALLY FUNDED THIS RESEARCH WORK*
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