Researchers at the Forschungszentrum Jülich have created a novel transistor made of a germanium-tin alloy that outperforms conventional switching elements in a number of ways. Charge transporters can move quicker in the material than in silicon or germanium, which empowers lower voltages in activity. As a result, the transistor appears to be a promising option for developing low-power, high-performance chips in the future, as well as quantum computers.
Moore’s Law, which is still in effect today, states that the number of transistors on a chip has roughly doubled every two years for the past 70 years. The circuits have gotten smaller in proportion, but this seems to be coming to an end soon.
“At this point, structures only measure 2 to 3 nanometers in size. This is roughly equivalent to the measurement of 10 iotas, which takes us to the furthest reaches of what is practical. It doesn’t get a lot more modest than this,” says Qing-Tai Zhao of the Peter Grünberg Establishment (PGI-9) at Forschungszentrum Jülich.
“We’ve now gotten to the point where structures are only 2 to 3 nanometers in size. This is roughly comparable to the diameter of ten atoms, bringing us to the limits of what is possible. It doesn’t get any more intimate than this.”Qing-Tai Zhao of the Peter Grünberg Institute (PGI-9) at Forschungszentrum Jülich.
Researchers have been searching for an alternative to silicon, the primary material utilized in the semiconductor industry, for some time. The idea is to find a material with better electronic properties that can be used in larger structures to achieve the same performance,” the professor explains.
The research focuses in part on germanium, which was used before computers were invented. In theory, electrons can move much faster in germanium than in silicon. Nonetheless, Qing-Tai Zhao and his associates have now gone above and beyond. To improve the electronic properties much further, they integrated tin iotas into the germanium gem cross section. At the Peter Grünberg Institute (PGI-9) of the Forschungszentrum Jülich, the method was developed several years ago.
According to Qing-Tai Zhao, “the germanium-tin system we have been testing makes it possible to overcome the physical limitations of silicon technology.” In tests, the germanium-tin semiconductor displays an electron versatility that is 2.5 times higher than that of a practically identical semiconductor made of unadulterated germanium.
The new material alloy’s compatibility with the existing chip fabrication CMOS process is another advantage. Tin, germanium, and silicon are all members of the same main group in the periodic table. With the existing production lines, the germanium-tin transistors could be integrated directly into conventional silicon chips.
There is high potential for the PCs to represent things to come.
Aside from old-style advanced PCs, quantum PCs could likewise profit from the germanium-tin semiconductor. There have been efforts for some time to directly integrate components of the control electronics on the quantum chip, which is used in a quantum computer at temperatures close to zero. According to measurements, transistors made of germanium-tin will perform significantly better than silicon transistors in these conditions.
Qing-Tai Zhao explains, “The challenge is to find a semiconductor whose switching can still be very fast with very low voltages at very low temperatures.” This switching curve flattens out for silicon below 50 kelvin. The transistors then require a high voltage and, consequently, a high power, which ultimately results in the heating-induced failure of the sensitive quantum bits. Germanium-tin performs better at these temperatures in estimations down to 12 Kelvin, and there are desires to utilize the material at even lower temperatures,” says Qing-Tai Zhao.
Moreover, the germanium-tin semiconductor is a further step towards optical on-chip information transmission. Numerous data networks already use light signals to transfer data because they are significantly faster and use less energy than electrical conductors. However, data is typically still sent electronically in the field of micro- and nanoelectronics.
A germanium-tin laser has already been developed by colleagues in Dr. Dan Buca’s Jülich working group, making it possible to optically transmit data directly on a silicon chip. Along with these lasers, a promising approach to the monolithic integration of nanoelectronics and photonics on a single chip is the germanium-tin transistor.
The paper has been accepted for publication in Communications Engineering.
More information: Mingshan Liu et al, Vertical GeSn nanowire MOSFETs for CMOS beyond silicon, Communications Engineering (2023). DOI: 10.1038/s44172-023-00059-2