Scientists at the Fraunhofer Institute for Applied Solid State Physics IAF have succeeded in developing a novel type of transistor with extremely high cut-off frequencies: metal oxide semiconductor HEMTs, in short MOSHEMTs. To achieve this, they have replaced the Schottky barrier of a conventional HEMT with an oxide. The result is a transistor that enables even smaller and more powerful devices. It has already reached record frequencies of 640 GHz. This technology is expected to advance next generation electronics.
The high frequency characteristics of high eElectron mobility transistors (HEMTs) have been steadily improved in the past years. The transistors have become increasingly faster by downscaling the gate length to 20 nm. However, a HEMT encounters a problem at such small structure sizes: The thinner the barrier material of InAlAs (indium aluminum arsenide) becomes, the more electrons leak from the current carrying channel through the gate.
These unwanted gate leakage currents have a negative impact on the efficiency and durability of the transistor, which renders further downscaling attempts impossible. The current transistor geometry of a conventional HEMT has reached its scaling limit.
Silicon MOSFETs (metal oxide semiconductor field effect transistors) are no stranger to this problem, either. However, they possess an oxide layer that can prevent unwanted leakage currents for longer than it is the case with HEMTs.
Combining advantages of both transistor technologies
Researchers at Fraunhofer IAF have combined the advantages of III-V semiconductors and Si MOSFETs and have replaced the Schottky barrier of a HEMT with an isolating oxide layer. The result is a new type of transistor: the metal oxide semiconductor HEMT, in short MOSHEMT.
»We have developed a new device which has the potential to exceed the efficiency of current HEMTs by far. The MOSHEMT allows us to downscale it even further, thus making it faster and more efficient,« explains Dr. Arnulf Leuther, researcher in the field of high-frequency electronics at Fraunhofer IAF.
With the new transistor technology, Leuther and his team have succeeded in achieving a record with a maximum oscillation frequency of 640 GHz. »This surpasses the global state of the art for any MOSFET technology, including silicon MOSFETs,« adds Leuther.
High barrier to overcome leakage currents
To overcome the gate leakage currents, the scientists had to use a material with a significantly higher barrier than the conventional Schottky barrier. They replaced the semiconductor barrier material with a combination of isolating layers consisting of aluminum oxide (Al2O3) and hafnium oxide (HfO2).
»This enables us to reduce the gate leakage current by a factor of more than 1000. Our first MOSHEMTs show a very high development potential, while current field effect transistor technologies have already reached their limit,« reports Dr. Axel Tessmann, scientist at Fraunhofer IAF.
The world’s first integrated circuit with MOSHEMTs
The extremely fast MOSHEMT is designed for the frequency range above 100 GHz and is therefore especially promising for novel communication, radar and sensor applications.
In the future, high-power devices will ensure a faster data transmission between radio towers and enable imaging radar systems for autonomous driving as well as higher resolution and precision of sensor systems.
While it will take some years until the MOSHEMT finds its way into commercial application, the researchers at Fraunhofer IAF have already succeeded to realize the world’s first amplifier MMIC (monolithic microwave integrated circuit) based on INGaAs MOSHEMTs for the frequency range between 200 and 300 GHz.
Anne-Julie Maurer | Fraunhofer-Institut für Angewandte Festkörperphysik IAF
Beyond the brim, Sombrero Galaxy's halo suggests turbulent past
21.02.2020 | NASA/Goddard Space Flight Center
10,000 times faster calculations of many-body quantum dynamics possible
21.02.2020 | Christian-Albrechts-Universität zu Kiel
The operational speed of semiconductors in various electronic and optoelectronic devices is limited to several gigahertz (a billion oscillations per second). This constrains the upper limit of the operational speed of computing. Now researchers from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, and the Indian Institute of Technology in Bombay have explained how these processes can be sped up through the use of light waves and defected solid materials.
Light waves perform several hundred trillion oscillations per second. Hence, it is natural to envision employing light oscillations to drive the electronic...
Most natural and artificial surfaces are rough: metals and even glasses that appear smooth to the naked eye can look like jagged mountain ranges under the microscope. There is currently no uniform theory about the origin of this roughness despite it being observed on all scales, from the atomic to the tectonic. Scientists suspect that the rough surface is formed by irreversible plastic deformation that occurs in many processes of mechanical machining of components such as milling.
Prof. Dr. Lars Pastewka from the Simulation group at the Department of Microsystems Engineering at the University of Freiburg and his team have simulated such...
Investigation of the temperature dependence of the skyrmion Hall effect reveals further insights into possible new data storage devices
The joint research project of Johannes Gutenberg University Mainz (JGU) and the Massachusetts Institute of Technology (MIT) that had previously demonstrated...
Researchers at Chalmers University of Technology, Sweden, recently completed a 5-year research project looking at how to make fibre optic communications systems more energy efficient. Among their proposals are smart, error-correcting data chip circuits, which they refined to be 10 times less energy consumptive. The project has yielded several scientific articles, in publications including Nature Communications.
Streaming films and music, scrolling through social media, and using cloud-based storage services are everyday activities now.
After helping develop a new approach for organic synthesis -- carbon-hydrogen functionalization -- scientists at Emory University are now showing how this approach may apply to drug discovery. Nature Catalysis published their most recent work -- a streamlined process for making a three-dimensional scaffold of keen interest to the pharmaceutical industry.
"Our tools open up whole new chemical space for potential drug targets," says Huw Davies, Emory professor of organic chemistry and senior author of the paper.
12.02.2020 | Event News
16.01.2020 | Event News
15.01.2020 | Event News
21.02.2020 | Medical Engineering
21.02.2020 | Health and Medicine
21.02.2020 | Physics and Astronomy