SUNY Poly researcher rockets technology into extreme environments
In Fatemeh (Shadi) Shahedipour-Sandvik’s SUNY Polytechnic Institute (SUNY Poly) laboratory, tiny things have huge impacts for electrical engineering.
As a professor in the nanoengineering constellation and interim dean of graduate studies, Shahedipour-Sandvik researches ways to improve electronic devices for use in extreme environments—think of on top of spacecraft or inside jet engines. By making specific molecular changes to semiconductors, a key piece of electronic circuitry, she and her team are creating components to run powerful electronics in the harshest of conditions.
As the name suggests, semiconductors fall somewhere between highly conductive metals like copper or gold and insulators, which prevent the flow of electricity. Unlike conductors, which provide constant electric flow, semiconductors can be turned “on” or “off.” This added regulator makes them crucial in controlling electronic devices from cell phones to LED lights to solar panels.
“Semiconductors are fascinating,” Shahedipour-Sandvik said. “Especially the novel materials we’re working with; it’s a really amazing material system because of the unique and extreme properties it offers.”
Shahedipour-Sandvik has spent her career exploring semiconductors, from her PhD research on semiconducting diamonds at the University of Missouri, to her lab’s current work on developing new technology for operation under harsh environments.
Since arriving at SUNY Poly in 2001, her research efforts have been well recognized by the university and the state. Her many awards include the 2006 Rising to Lead Best Technologist Award from the city of Albany’s Alliance of Technology and Women and a 2012 Excellence in Research award from the University at Albany. Shahedipour-Sandvik was also named the first Presidential Fellow at the Research Foundation for the 2013-14 academic year.
Most recently, Shahedipour-Sandvik and colleagues were awarded $720,000 by the U.S. Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E) to study next-generation semiconductors for application in high power electronics. Unlike the silicon semiconductors found in many personal electronic devices, she is developing components with a gallium nitride (GaN) base.
“In comparison to silicon, GaN can be used to create devices that work in harsh environments,” Shahedipour-Sandvik said, referring to electronic “noise” appearing in silicon semiconductors under extreme conditions. This noise comes from unwanted current flowing when the semiconductor should be in an “off” state, compromising device function.
“Not only does GaN have fascinating properties, the system holds great promises for technological advances,” she said.
Semiconductors consist of a lattice of atoms, like silicon or gallium and nitride for GaN, with different elements incorporated into the lattice through a process called doping. With two types of doping, “p-type” and “n-type”, current flow can be controlled by the choice of element used as a dopant. The relatively short length of the bonds in the GaN lattice is key to its ability to withstand harsh environments.
Working with collaborators from SUNY Poly, the Army Research Lab, Drexel University, and Gyrotron Technology, Inc. (Gyrotron), Shahedipour-Sandvik is hoping to overcome one of the major challenges in creating these next-generation devices: effective p-type doping in the GaN base.
Fortunately Gyrotron has a new method for activating the dopant, magnesium, introduced through a process called implantation. By using microsecond pulses of electromagnetic waves, the GaN base temperatures may be increased to over 1300 degrees Celsius. Along with a method to stabilize the lattice, the team hopes to get high levels of doping without damaging the GaN lattice.
Additionally, Shahedipour-Sandvik will build the new semiconductors on a GaN base, which ensures the best electricity flow and highest performance as compared to bases of a different material than the lattice. Although GaN bases are expensive and hard to come by, Shahedipour-Sandvik has high hopes: “even if these devices are made on small areas in low volume, they’re still going to be very impactful.”
With this diverse team focused on developing next-generation semiconductors, this new technology may soon become a reality, Shahedipour-Sandvik said.
“It really takes a team that has complementary expertise to fully understand the fundamentals of the GaN system and overcome its inherent challenges.”
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