Silicon transistors, crucial components for amplifying and switching signals, play a vital role in the majority of modern digital devices, including smartphones and vehicles. However, there is an intrinsic physical limitation that hinders the operation of transistors at a certain voltage threshold, impeding further advancements in silicon-based semiconductor technology.
The phenomenon known as “Boltzmann tyranny” severely limits the efficiency of computer systems and other electronic devices, exacerbating issues in an era where rapid computation is crucial for the development and deployment of artificial intelligence technologies.
To overcome the fundamental limitations imposed by silicon, MIT scientists developed a novel three-dimensional transistor using a single set of ultra-thin semiconductor materials.
Researchers have developed innovative gadgets that feature vertically aligned nanowires only a few nanometers in size, capable of achieving efficiencies comparable to those of cutting-edge silicon transistors while operating efficiently at significantly lower voltage levels than traditional devices.
According to Yanjie Shao, an MIT postdoctoral researcher and lead author of a recent study on the innovative transistors, this breakthrough has the potential to replace silicon with significantly improved energy efficiency, mirroring all the capabilities currently available in silicon technology.
The transistors harness the principles of quantum mechanics to achieve concurrent benefits of low-voltage operation and high efficiency within a remarkably small area, confined to just a few square inches. nanometers. The minuscule size of these 3D transistors enables the packing of numerous units onto a single PC chip, resulting in speedy, high-performance electronics that are also more power-efficient.
“With current understanding of physics, the limits to what we can achieve seem to be reached.” Yanjie’s findings suggest that humanity is capable of achieving far more, but this requires harnessing fundamentally distinct physical principles. According to senior writer Jesús del Alamo, the Donner Professor of Engineering at MIT’s Department of Electrical Engineering and Computer Science, “various challenges must be overcome for this method to be industrialized sooner or later. However, conceptually, it truly is a breakthrough.”
The authors are joined on this paper by Ju Li, Tokyo Electrical Power Company Professor of Nuclear Engineering and professor of materials science and engineering at MIT; EECS graduate student Hao Tang; MIT postdoctoral researcher Baoming Wang; and professors Marco Pala and David Esseni from the University of Udine in Italy. The analysis
In most digital devices, silicon-based transistors operate as binary switches, controlling the flow of electrical current. The application of a voltage to a transistor induces electrons to traverse an energy barrier from one side to the other, effectively toggling the device from an “off” to an “on” state. This fundamental mechanism enables transistors to represent binary digits, facilitating computation and driving the operation of complex digital systems?
The transistor’s switching slope reveals the distinctiveness of the transition from “off” to “on”. As the slope steepens, a significantly reduced voltage is necessary to trigger the transistor, resulting in a substantially enhanced voltage efficiency.
While electrons can freely pass through an energy barrier under certain conditions, Boltzmann’s tyranny necessitates a minimum voltage threshold to modulate the transistor effectively at room temperature.
Researchers at MIT exploited the physical limitations of silicon by employing a distinct combination of semiconductors, specifically gallium antimonide and indium arsenide, and engineered devices that capitalised on the quantum mechanical property of quantum tunnelling.
Quantum tunneling enables electrons to traverse seemingly impenetrable barriers, defying classical notions of spatial confinement. Researchers have successfully fabricated tunneling transistors that exploit this phenomenon to induce electrons to tunnel through the energy barrier rather than overcome it.
“Now, flipping the system on and off will be as easy as can be,” Shao explains.
While tunneling transistors can facilitate abrupt switching transitions, their typical operation at low current levels compromises the overall efficiency of digital systems. High-quality present layers are crucial in fabricating highly efficient transistor switches capable of meeting the most stringent requirements.
Engineers leveraged the cutting-edge capabilities at MIT.nano, the institution’s premier facility for nanoscale analysis, to meticulously control the three-dimensional geometry of their transistors, fabricating intricate vertical nanowire heterostructures with a remarkably narrow diameter of just 6 nanometers. Researchers claim that these tiny devices are currently the most diminutive 3D transistors recorded to date.
Their precise engineering allowed for the simultaneous achievement of steep switching slopes and high currents. This phenomenon of quantum confinement holds significant promise for various applications.
Quantum confinement occurs when an electron is restricted to a region so minuscule that it is unlikely to tunnel through. As the electron’s mass increases and the fabric’s properties adapt, the electron gains the ability to traverse a previously insurmountable barrier with enhanced ease.
Due to their minuscule size, researchers can successfully engineer a robust quantum confinement effect, simultaneously fabricating an extremely thin barrier.
According to Shao, the team has ample room for designing heterogeneous structures, enabling them to create extremely thin tunnel barriers that facilitate high current flows.
The precise fabrication of miniature devices that could accomplish this feat was the primary challenge.
“We’ve successfully ventured into the realm of single-nanometer dimensions with these groundbreaking findings.” Only a handful of teams worldwide possess the expertise to fabricate high-quality transistors with such varying characteristics. Professor del Alamo notes that Yanjie has achieved remarkable success in designing exceptionally tiny and highly functional transistors.
The researchers’ analysis revealed that the steepness of the transition slope fell short of the benchmark achievable with conventional silicon transistors. The devices exhibited a remarkable performance boost of around 20 times greater than their tunneling transistor counterparts.
“For the first time, our team has achieved such a remarkable degree of sharp switching steepness with this innovative design,” Shao explains.
Researchers are working to refine their fabrication techniques to ensure the creation of more consistent and uniform transistors across an entire microchip. Even minute fluctuations of just one nanometer in these miniature devices can significantly alter the behavior of electrons, ultimately impacting system performance. Researchers are also investigating vertical fin-shaped structures and vertical nanowire transistors, which could potentially improve the consistency of devices on a chip.
This groundbreaking research decisively propels the field forward, significantly amplifying the efficacy of the broken-gap tunnel subject impact transistor (TFET). The circuit demonstrates high impedance to ground and a significant increase in output current when the input is driven. The revised text: The fabrication of broken-gap tunnel field-effect transistors (TFETs) underscores the critical importance of small dimensions, excessive confinement, and low-defectivity supplies and interfaces. According to Aryan Afzalian, principal member of imec’s nanoelectronics analysis group, these options have been achieved through meticulous control at the nanometer scale, as part of a well-mastered course.
The research findings presented in this report are made possible, in part, through a collaborative effort with Intel Corporation.
