Although silicon semiconductors are nearly universal in modern electronics, devices made from silicon have limitations—including that they cease to function properly at very high temperatures.
One promising alternative are semiconductors made from combinations of aluminum, gallium, and indium with nitrogen to form aluminum nitride (AlN), gallium nitride (GaN), and indium nitride (InN), which are stronger and more stable than their silicon counterparts, function at high temperatures, are piezoelectric (that is, generate voltage under mechanical force), and are transparent to, and can emit, visible light.
Conventional processes for producing AIN layers run at temperatures as high as 1150 degrees Celsius, and offer limited control over the thickness of the layers. Now a new technique, described in the AIP Publishing journal Applied Physics Letters, offers a way to produce high-quality AlN layers with atomic-scale thickness and at half the temperature of other methods.
Neeraj Nepal and colleagues of the United States Naval Research Laboratory in Washington, D.C. formed AIN layers using atomic layer epitaxy (ALE), in which materials are "grown," layer-by-layer, by sequentially employing two self-limiting chemical reactions onto a surface.
"For instance to grow aluminum nitride, you would inject a pulse of an aluminum precursor into the growth zone where it would coat all surfaces," explained Nepal. "After purging any excess aluminum precursor away, you would then ‘build’ the crystal by injecting a pulse of the nitrogen precursors into the growth zone, where it reacts with the aluminum precursor at the surface to form a layer of AlN. Then you’d purge any excess nitrogen and reaction products away and repeat the process."
With this process, the researchers produced a material with qualities similar to those synthesized at much higher temperatures, but under conditions that allow it to be integrated in new ways for the fabrication of devices for technologies such as transistors and switches.
The work, Nepal says, expands the potential for new advanced specialty materials that could be used, for example, in next-generation high-frequency radiofrequency electronics, such as those used for high-speed data transfer and cell phone services.
The article, "Epitaxial Growth of AlN Films via Plasma-assisted Atomic Layer Epitaxy" by N. Nepal, S. B. Qadri, J. K. Hite, N.A. Mahadik, M.A. Mastro, and C. R. Eddy, Jr. appears in the journal Applied Physics Letters. See: http://dx.doi.org/10.1063/1.4818792ABOUT THE JOURNAL
Jason Socrates Bardi | Newswise
Siberian scientists suggested a new method for synthesizing a promising magnetic material
23.01.2018 | Siberian Federal University
Complex tessellations, extraordinary materials
23.01.2018 | Technische Universität München
Physicists have developed a technique based on optical microscopy that can be used to create images of atoms on the nanoscale. In particular, the new method allows the imaging of quantum dots in a semiconductor chip. Together with colleagues from the University of Bochum, scientists from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute reported the findings in the journal Nature Photonics.
Microscopes allow us to see structures that are otherwise invisible to the human eye. However, conventional optical microscopes cannot be used to image...
On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.
We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
23.01.2018 | Earth Sciences
23.01.2018 | Life Sciences
23.01.2018 | Materials Sciences