Scientists are turning the century-old material into a thin film for the next generation of memory and logic devices
Silicone-based computer chips that enhance our modern devices a large amount of energy is required to work. Despite the ever-improving computational efficiency, information technology is projected to consume about 25% of all primary energy produced by 2030. Researchers in the microelectronics and materials science communities are looking for ways to sustainably manage the global need for computing power.
To reduce this digital demand, the sacred goal is the development of lower-voltage microelectronics, which require less energy and are the main goal of efforts to go beyond today’s most modern CMOS (complementary metal-oxide semiconductor). devices.
Non-silicone materials with attractive properties are available for memory and logic devices; but their general bulk form still requires large voltages to manipulate, which makes them incompatible with modern electronics. The design of thin-film alternatives that perform well not only at low operating voltages, but also in microelectronic devices, remains a challenge.
Now, a team of researchers from Lawrence Berkeley National Laboratory (Berkeley Laboratory) and UC Berkeley have identified an energy-saving route by synthesizing a thin-layer version of the popular material whose features are exactly what future generation devices need. .
Barium titanate (BaTiO) was first discovered more than 80 years ago3) have been used in electronic circuits, ultrasonic generators, transducers and even various capacitors for sonar.
The crystals of the material react quickly to a small electric field, and even if the applied field is removed, they change the direction of the charged atoms that make up the material in a reversible but constant manner. This provides a way to switch between logic and memory devices, for example, between “0” and “1” states – but it still requires voltages greater than 1000 millivolts (mV).
Wanting to use these features in microchips, a team led by Berkeley Labs has developed a way to create BaTiO films.3 only 25 nanometers thin – less than a thousandth of the width of human hair – the orientation or polarization of the charged atoms changes as quickly and efficiently as in the bulk version.
“We know about BaTiO3 is the best part of the century, and we have known for over 40 years how to make thin layers of this material. But so far no one has been able to make a film that is close to a collectively available structure or performance, “said Lane Martin, a faculty scientist and professor of materials science at Berkeley Laboratory’s Department of Materials Science (MSD).
Historically, synthesis attempts have resulted in films containing higher concentrations of “defects” – points where the structure differed from the idealized version of the material – compared to the bulk versions. Such a high concentration of defects adversely affects the performance of thin films. Martin and colleagues developed an approach to enlarging films that limited these shortcomings. The results were published in the journal Nature Materials.
To best understand what it takes to produce a low-defect BaTiO3 In thin films, researchers have developed a process called pulsed-laser deposition. The emission of a strong beam of ultraviolet laser light on the ceramic target of BaTiO3 causes the material to turn into plasma, which transfers the atoms from the target to the surface to enlarge the film. “It’s a versatile tool where we can nail a lot of buttons as the film grows and see what’s most important to control the properties,” Martin said.
Martin and his colleagues demonstrated that their method could achieve precise control over the structure, chemistry, thickness, and interface of the assembled film with metal electrodes. Using tools from the National Electron Microscopy Center at the Molecular Casting Plant of the Berkeley Laboratory, the researchers split each deposited sample in half and looked at the structure of the atoms to find a version that accurately mimicked an extremely thin slice of mass.
“It’s a lot of fun to think that we can take these classic materials that we think we know everything and turn them into new approaches to prepare and characterize them,” Martin said.
Finally, by posting the film BaTiO3 Between the two metal sheets, Martin and his team created small capacitors – electronic components that quickly store and release energy in the circuit. The application of voltages of 100 mV or less and the measurement of the resulting current showed that the polarization of the film changes within two billionths of a second and could potentially be faster – competitive with today’s computers required to access memory or perform calculations.
The work pursues a larger purpose, such as the creation of materials with low switching voltages and the study of how interfaces with metal components necessary for devices affect such materials. “This is a good early victory in the search for low-power electronics that go beyond what is possible with silicon-based electronics today,” Martin said.
“Unlike our new devices, the capacitors used in chips today do not store their data until voltage is applied,” Martin said. Existing technologies generally operate between 500 and 600 mV, while the thin film version can operate between 50 and 100 mV or less. Together, these measurements demonstrate the successful optimization of tension and polarity strength – an exchange, especially in thin materials.
The team then plans to thin out the material to match the real devices on the computers and learn how it behaves in these small sizes. At the same time, they asked Intel Corp. to test the capabilities of first-generation electronic devices. will work with employees in companies such as “If you can make every logic operation on a computer a million times more efficient, think about how much energy you save. That’s why we’re doing it, “said Martin.
This research was supported by the Science Department of the US Department of Energy (DOE). The molecular casting plant is a user facility of the DOE Science Department at Berkeley Laboratory.
The Berkeley Lab’s “Beyond Moore’s Law” initiative aims to identify paths that lead to ultra-low power logic in memory elements. “We have to go to low-voltage work because that’s what scales energy,” said Ramamoorthy Ramesh, a senior lecturer at Berkeley Laboratory and professor of physics and materials science and engineering at UC Berkeley. “For the first time, this work demonstrated the transition area of BaTiO, a model material3 on a suitable platform with a voltage below 100 mV.
Article courtesy of Lawrence Berkeley National Laboratory (Berkeley Lab).
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Selected image: Silicon waffle macro by Laura Ockel on Unsplash
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