Arthur T Knackerbracket has processed the following story:
Silicon transistors, which are used to amplify and switch signals, are a critical component in most electronic devices, from smartphones to automobiles. But silicon semiconductor technology is held back by a fundamental physical limit that prevents transistors from operating below a certain voltage.
This limit, known as “Boltzmann tyranny,” hinders the energy efficiency of computers and other electronics, especially with the rapid development of artificial intelligence technologies that demand faster computation.
In an effort to overcome this fundamental limit of silicon, MIT researchers fabricated a different type of three-dimensional transistor using a unique set of ultrathin semiconductor materials.
Their devices, featuring vertical nanowires only a few nanometers wide, can deliver performance comparable to state-of-the-art silicon transistors while operating efficiently at much lower voltages than conventional devices.
“This is a technology with the potential to replace silicon, so you could use it with all the functions that silicon currently has, but with much better energy efficiency,” says Yanjie Shao, an MIT postdoc and lead author of a paper on the new transistors.
[...] In electronic devices, silicon transistors often operate as switches. Applying a voltage to the transistor causes electrons to move over an energy barrier from one side to the other, switching the transistor from “off” to “on.” By switching, transistors represent binary digits to perform computation.
A transistor’s switching slope reflects the sharpness of the “off” to “on” transition. The steeper the slope, the less voltage is needed to turn on the transistor and the greater its energy efficiency.
But because of how electrons move across an energy barrier, Boltzmann tyranny requires a certain minimum voltage to switch the transistor at room temperature.
To overcome the physical limit of silicon, the MIT researchers used a different set of semiconductor materials — gallium antimonide and indium arsenide — and designed their devices to leverage a unique phenomenon in quantum mechanics called quantum tunneling.
Quantum tunneling is the ability of electrons to penetrate barriers. The researchers fabricated tunneling transistors, which leverage this property to encourage electrons to push through the energy barrier rather than going over it.
But while tunneling transistors can enable sharp switching slopes, they typically operate with low current, which hampers the performance of an electronic device. Higher current is necessary to create powerful transistor switches for demanding applications.
Using tools at MIT.nano, MIT’s state-of-the-art facility for nanoscale research, the engineers were able to carefully control the 3D geometry of their transistors, creating vertical nanowire heterostructures with a diameter of only 6 nanometers. They believe these are the smallest 3D transistors reported to date.
Such precise engineering enabled them to achieve a sharp switching slope and high current simultaneously. This is possible because of a phenomenon called quantum confinement.
Quantum confinement occurs when an electron is confined to a space that is so small that it can’t move around. When this happens, the effective mass of the electron and the properties of the material change, enabling stronger tunneling of the electron through a barrier.
Because the transistors are so small, the researchers can engineer a very strong quantum confinement effect while also fabricating an extremely thin barrier.
“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,” Shao says.
[...] The researchers are now striving to enhance their fabrication methods to make transistors more uniform across an entire chip. With such small devices, even a 1-nanometer variance can change the behavior of the electrons and affect device operation. They are also exploring vertical fin-shaped structures, in addition to vertical nanowire transistors, which could potentially improve the uniformity of devices on a chip.
(Score: 4, Interesting) by VLM on Thursday November 14, @01:05PM
The article's journalist and/or AI seemed confused about the paper and appears to have written a very generic explanation of a FET.
Helpfully the (probably taxpayer funded) journal article is behind a paywall but I get get access to an abstract.
I think what is going on here is your typical MOSFET high power transistor has a gate drive voltage Vgs(th) around "maybe 4 volts" which sucks if you only have 3.3 volt logic supplies etc. Yes, I know, for switching DC the gate is essentially infinite resistance so the voltage "doesn't matter" however for switching AC like in a switching power supply or fast digital logic the capacitance matters. Ohms law applies to all (simplification...) so AC current drawn by the gate is voltage (which is over 4 V ish on old MOSFETs) divided by capacitive reactance and the lower the gate voltage the lower the AC drive current and power is volts times amps so lowering the drive voltage should dramatically lower the power drawn by switching the gate.
The article abstract seems to imply the equivalent of a MOSFET's Vgs(th) for this new thing is on the order of 0.3 volts. So figure "somewhat less than 1/10th the gate drive voltage" assuming I'm reading this correctly which should be about 1/10th the power dissipated due to gate drive (no effect on ohmic losses, probably, so this won't remove 9/10 of existing losses but it'll remove some maybe up to a fifth of total supply losses?)
Possibly it'll tip the balance of optimum supply design so you could switch at even faster frequencies maybe more efficient? Maybe switching power supplies made with these new transistors could possibly dissipate 1/3 less heat under absolutely ideal conditions?
Yeah you can see why he doesn't provide numbers; "well over 80%" is already typical for a switching power supply with old technology, so by "much better" he likely does not mean 160% efficient or 800% efficient both of which would be very impressive. So... maybe in the future, slightly larger power supplies won't need cooling fans, maybe, in the far "Star Trek" future. More likely they'll just deploy more power into CPUs and the like resulting in more computation per watt for the overall system but total "power outlet" wattage remains the same.
There seem to be some assumptions here like bulk ohmic losses are not any worse than existing industrially produced FETs and gate capacitance won't be any higher. I'm not sure why those assumptions are assumed. Probably discussed in the journal article behind the paywall.
(Score: 4, Funny) by looorg on Thursday November 14, @01:30PM (1 child)
The new electronic nightmare -- hand soldering nano-scale transistors. I assume they are for inside other component and not as a standalone component. Otherwise I don't know how you would ever solder or attach them to anything, without destroying them or bridging them or just manage to attach them.
(Score: 2) by Freeman on Thursday November 14, @02:53PM
Essentially you just don't. Theoretically you might could with the right tools, but even finding the "right thing" to solder could be a chore.
Joshua 1:9 "Be strong and of a good courage; be not afraid, neither be thou dismayed: for the Lord thy God is with thee"
(Score: 5, Informative) by ChrisMaple on Thursday November 14, @04:00PM
Judging by the scale, 6 nm, the devices are for things like CPUs, not high power drivers. Modern CPUs have core voltages around 1.3 volts for standard performance and can't run full speed at lower voltages. Take the voltage too low, and they can't be made to run at all. The energy for a logic transition is 0.5*C*V^2. If the capacitance of the new device is about the same as existing devices, the energy ratio of the new devices to the old is (0.3/1.3)^2 = 0.053. That's a huge improvement. From the Nature abstract, the materials are GaSb/InAs.
That's all assuming the devices are voltage controlled, will be available in the equivalent of both n-channel and p-channel devices, and don't have significant leakage current when turned off.
(Score: 2) by Rich on Friday November 15, @12:06PM
Transisors with "Tunneling barrier"s sound a lot like flash memory. We know this degrades with use. Is this newfangled thingy an entirely different topology that isn't subject to such degradation and suitable for general use?