Scientists at the Fraunhofer Institute for Applied Solid State Physics IAF have achieved what was previously considered impossible: they are the first in the world who have managed to manufacture aluminum scandium nitride (AlScN) via metal-organic chemical vapor deposition (MOCVD). Devices based on AlScN are considered to be the next generation of power electronics. With this breakthrough, Fraunhofer IAF takes a decisive step towards its goal of developing power electronics based on AlScN transistors for industrial applications.
Transistors based on AlScN are promising for various industrial applications, such as data transfer, satellite communication, radar systems or autonomous driving, especially since current devices based on silicon (Si) are reaching their physical limit in these applications.
One reason for this is the size of Si devices, which cannot be reduced any more according to the current state of research. If the ever-increasing amounts of data had to be processed with the current Si technology, the server rooms would occupy such a large area that it would be economically and ecologically unstainable.
So-called HEMTs (high electron mobility transistors) surpass the possibilities of Si devices by far. The key to the success of HEMT structures lies in the materials they are based on. AlScN has exceptional properties, allowing higher carrier concentrations than other materials. In the future, significantly more powerful and efficient HEMTs will be realized based on AlScN.
Previous manufacturing processes have failed due to quality and productivity
The production of AlScN involves fundamental challenges. The state-of-the-art production process grows AlScN layers via sputtering. Unfortunately, the quality of these layers is insufficient for electronic applications such as LEDs and high-power transistors. An alternative method is to produce AlScN via molecular beam epitaxy (MBE). With this process, high amounts of scandium can be incorporated in the compound. The quality is also sufficient for the production of microelectronic devices. However, the procedure is very complex and the productivity too low for industrial scale productions.
Metal-organic chemical vapor deposition promises industrial-grade production
The production of AlScN via MOCVD promises not only the necessary quality, but also sufficient productivity for industrial applications. “We knew that previous attempts by other scientists to produce gallium scandium nitride via MOCVD had failed. We also know that many scientists all over the world are working to develop AlScN transistors, but no one before us has succeeded in doing it by using MOCVD, even though it is a very promising approach for industry”, explains Dr Stefano Leone, group leader at Fraunhofer IAF.
During the MOCVD procedure gases are guided across a heated wafer. Through the heat exposure distinct molecules are released from the gas and integrated into the crystalline structure of the wafer. The crystal structure can be precisely adjusted by regulating the gas flow, temperature and pressure. Furthermore, the quick change of gas allows to grow different material layers on top of each other.
Fraunhofer IAF achieves novelty
The challenge for the researchers at Fraunhofer IAF: there is no gas source for scandium. The molecules (precursors) for scandium are very large and difficult to bring into the gas phase. “We studied the best possible precursor for scandium and planned adjustments of our MOCVD reactor for the necessary procedure. We did a lot of research and had numerous discussions until we developed a setup that we are now even patenting. We have now succeeded in growing AlScN layers via MOCVD with a very high crystal quality and the right amount of scandium in order to develop the next generation of power transistors”, says Leone, pleased with the achievement. The MOCVD system at Fraunhofer IAF has been modified by the research group to enable a high-quality and reproducible AlScN production process.
First AlScN layers for transistors from the MOCVD
After the successful deposition of AlScN in the MOCVD system, the first AlScN layers for transistors were produced. The layers already reach promising results with a sheet resistance of ~200 ohm/sq., a mobility of ~600 cm²/Vs and a charge carrier density of ~4,0 x 10¹³ cm⁻². The current goal of the scientists is to reduce the sheet resistance and to further increase the mobility and material quality. This will improve the performance of future transistors and Fraunhofer IAF will take a significant step towards its goal of providing AlScN HEMTs for industrial power electronic applications.
Jennifer Funk | Fraunhofer-Institut für Angewandte Festkörperphysik IAF
New gravitational-wave model can bring neutron stars into even sharper focus
22.05.2020 | University of Birmingham
Electrons break rotational symmetry in exotic low-temp superconductor
20.05.2020 | DOE/Brookhaven National Laboratory
Thomas Heine, Professor of Theoretical Chemistry at TU Dresden, together with his team, first predicted a topological 2D polymer in 2019. Only one year later, an international team led by Italian researchers was able to synthesize these materials and experimentally prove their topological properties. For the renowned journal Nature Materials, this was the occasion to invite Thomas Heine to a News and Views article, which was published this week. Under the title "Making 2D Topological Polymers a reality" Prof. Heine describes how his theory became a reality.
Ultrathin materials are extremely interesting as building blocks for next generation nano electronic devices, as it is much easier to make circuits and other...
Scientists took a leukocyte as the blueprint and developed a microrobot that has the size, shape and moving capabilities of a white blood cell. Simulating a blood vessel in a laboratory setting, they succeeded in magnetically navigating the ball-shaped microroller through this dynamic and dense environment. The drug-delivery vehicle withstood the simulated blood flow, pushing the developments in targeted drug delivery a step further: inside the body, there is no better access route to all tissues and organs than the circulatory system. A robot that could actually travel through this finely woven web would revolutionize the minimally-invasive treatment of illnesses.
A team of scientists from the Max Planck Institute for Intelligent Systems (MPI-IS) in Stuttgart invented a tiny microrobot that resembles a white blood cell...
By studying the chemical elements on Mars today -- including carbon and oxygen -- scientists can work backwards to piece together the history of a planet that once had the conditions necessary to support life.
Weaving this story, element by element, from roughly 140 million miles (225 million kilometers) away is a painstaking process. But scientists aren't the type...
Study co-led by Berkeley Lab reveals how wavelike plasmons could power up a new class of sensing and photochemical technologies at the nanoscale
Wavelike, collective oscillations of electrons known as "plasmons" are very important for determining the optical and electronic properties of metals.
Proteins, the microscopic “workhorses” that perform all the functions essential to life, are team players: in order to do their job, they often need to assemble into precise structures called protein complexes. These complexes, however, can be dynamic and short-lived, with proteins coming together but disbanding soon after.
In a new paper published in PNAS, researchers from the Max Planck Institute for Dynamics and Self-Organization, the University of Oxford, and Sorbonne...
19.05.2020 | Event News
07.04.2020 | Event News
06.04.2020 | Event News
22.05.2020 | Physics and Astronomy
22.05.2020 | Materials Sciences
22.05.2020 | Materials Sciences