A new approach to integrated circuits, combining atoms of semiconductor materials into nanowires and structures on top of silicon surfaces, shows promise for a new generation of fast, robust electronic and photonic devices.
Engineers at the University of California, Davis, have recently demonstrated three-dimensional nanowire transistors using this approach that open exciting opportunities for integrating other semiconductors, such as gallium nitride, on silicon substrates.
"Silicon can't do everything," said Saif Islam, professor of electrical and computer engineering at UC Davis. Circuits built on conventionally etched silicon have reached their lower size limit, which restricts operation speed and integration density. Additionally, conventional silicon circuits cannot function at temperatures above 250 degrees Celsius (about 480 degrees Fahrenheit), or handle high power or voltages, or optical applications.
The new technology could be used, for example, to build sensors that can operate under high temperatures, for example inside aircraft engines.
"In the foreseeable future, society will be dependent on a variety of sensors and control systems that operate in extreme environments, such as motor vehicles, boats, airplanes, terrestrial oil and ore extraction, rockets, spacecraft, and bodily implants," Islam said.
Devices that include both silicon and nonsilicon materials offer higher speeds and more robust performance. Conventional microcircuits are formed from etched layers of silicon and insulators, but it's difficult to grow nonsilicon materials as layers over silicon because of incompatibilities in crystal structure (or "lattice mismatch") and differences in thermal properties.
Instead, Islam's laboratory at UC Davis has created silicon wafers with "nanopillars" of materials such as gallium arsenide, gallium nitride or indium phosphide on them, and grown tiny nanowire "bridges" between nanopillars.
"We can't grow films of these other materials on silicon, but we can grow them as nanowires," Islam said.
The researchers have been able to make these nanowires operate as transistors, and combine them into more complex circuits as well as devices that are responsive to light. They have developed techniques to control the number of nanowires, their physical characteristics and consistency.
Islam said the suspended structures have other advantages: They are easier to cool and handle thermal expansion better than planar structures — a relevant issue when mismatched materials are combined in a transistor.
The technology also leverages the well-established technology for manufacturing silicon integrated circuits, instead of having to create an entirely new route for manufacturing and distribution, Islam said.
The work is described in a series of recent papers in the journals Advanced Materials, Applied Physics Letters and IEEE Transactions on Nanotechnology with co-authors Jin Yong Oh at UC Davis; Jong-Tae Park, University of Incheon, South Korea; Hyun-June Jang and Won-Ju Cho, Kwangwoon University, South Korea. Funding was provided by the U.S. National Science Foundation and the government of South Korea.
UC Davis is a global community of individuals united to better humanity and our natural world while seeking solutions to some of our most pressing challenges. Located near the California state capital, UC Davis has more than 34,000 students, and the full-time equivalent of 4,100 faculty and other academics and 17,400 staff. The campus has an annual research budget of over $750 million, a comprehensive health system and about two dozen specialized research centers. The university offers interdisciplinary graduate study and 99 undergraduate majors in four colleges and six professional schools.
Andy Fell | Eurek Alert!
How to maximize the superconducting critical temperature in a molecular superconductor
20.04.2015 | Tohoku University
Diamonds get more beautiful with laser lamps
16.04.2015 | Heraeus Noblelight GmbH
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and the University of Konstanz are working on storing and processing information on the level of single molecules to create the smallest possible components that will combine autonomously to form a circuit. As recently reported in the academic journal Advanced Science, the researchers can switch on the current flow through a single molecule for the first time with the help of light.
Dr. Artur Erbe, physicist at the HZDR, is convinced that in the future molecular electronics will open the door for novel and increasingly smaller – while also...
Cells of the vascular system of vertebrates can fuse with themselves. This process, which occurs when a blood vessel is no longer necessary and pruned, has now been described on the cellular level by Prof. Markus Affolter from the Biozentrum of the University of Basel. The findings of this study have been published in the journal “PLoS Biology”.
The vascular system is the supply network of the human organism and delivers oxygen and nutrients to the last corners of the body. So far, research on the...
Astronomers from Chalmers University of Technology have used the giant telescope Alma to reveal an extremely powerful magnetic field very close to a supermassive black hole in a distant galaxy
Astronomers from Chalmers University of Technology have used the giant telescope Alma to reveal an extremely powerful magnetic field very close to a...
A team of physicists from MPQ, Caltech, and ICFO proposes the combination of nano-photonics with ultracold atoms for simulating quantum many-body systems and creating new states of matter.
Ultracold atoms in the so-called optical lattices, that are generated by crosswise superposition of laser beams, have been proven to be one of the most...
According to new research out of the Texas A&M Health Science Center College of Medicine, that is indeed the case. Chetan Jinadatha, M.D., M.P.H., assistant...
13.04.2015 | Event News
25.03.2015 | Event News
19.03.2015 | Event News
20.04.2015 | Physics and Astronomy
20.04.2015 | Architecture and Construction
20.04.2015 | Physics and Astronomy