Energy Innovation Synergy: Sanjay Krishna

Sanjay Krishna

Teaching the next generation of engineers to excel is just one facet of an SOE professor’s job. With his history of innovations, interdisciplinary collaborations, multiple outreach projects, teaching responsibilities, and a fledgling company, Sanjay Krishna, professor in the Electrical and Computer Engineering Department and associate director of the Center for High Technology Materials (CHTM), demonstrates the synergy of innovative teaching and research.

A Quantum Change in Infrared Detection

Krishna’s current research at CHTM is developing an “infrared retina” that will encode spectral information similar to the cones in the human eye. This new camera features the next generation of infrared detectors made with two nanoscale materials: quantum dots and superlattices. Both technologies can be engineered as sensors and incorporated into detection devices, like cameras, to clearly “see” things the human eye cannot, such as the top of a mountain through thick fog or a repository of noxious chemicals through a brick wall. Quantum dots, just 10-20 nanometers in diameter, are based on a more mature GaAs (gallium arsenide) technology that can work at a higher temperature, allowing for a smaller device with less cooling equipment, useful for firefighting or surveillance operations. Superlattices, alternate stacks of semiconductor material just few nanometers thick, have a higher quantum efficiency so they can detect lower infrared signals, ideal for faint background applications such as astronomy, where scientists use infrared imaging to see distant galaxies. CHTM has three molecular beam epitaxy (MBE) machines, which use atomic beams from hot elemental sources of gallium, aluminum, indium, antimony, and arsenic to grow nanoscale crystals on a heated wafer in an ultra-high vacuum environment. Once the dots and lattices are constructed, the team makes electrical connections between them and bonds them to a silicon circuit to create a nanoscale infrared detector. Five years ago, the team used the circuits to make the first-ever infrared camera using a computer chip loaded with quantum dots. The infrared detector chips can be used interchangeably in an infrared test bed about the size of an early-model video camera. The two technologies will be adapted for different markets.

A Multidisciplinary Team

Krishna is coordinating the many phases of this Department of Defense-funded research with a multidisciplinary team of researchers, graduate students, and undergraduates. “Designing these technologies requires a lot of physics, quantum mechanics, and materials engineering,” he says. Beyond the different skills each researcher brings to the table, Krishna says bridging disciplines creates new viewpoints. “We are all trained in a certain way in our own disciplines.

Having someone from outside our discipline gives a great dimension to the work because they see a different perspective and that’s very helpful,” he explains. Ultimately, the researchers hope the nanosensors will be the foundation of a sophisticated infrared retina that can be inserted into highpowered detection devices. Much like the human eye, the infrared retina would include rods and cones to detect color. The “rods” and “cones” would be made of quantum dots and superlattices engineered with different spectral capabilities so they could detect polarization, gain, and phase information.

The potential for Krishna’s research is already being recognized by industry. “I think there is a big future in this research because there is a strong interest by the Department of Defense to migrate infrared technology to the materials that Sanjay Krishna is pioneering,” comments Ed Smith, senior principal engineer at Raytheon Vision Systems. Smith, who has worked with Krishna for five years, adds that Krishna’s group is unique compared to other researchers who generally focus on one facet of the research. “Krishna’s group has a well-rounded skill set and a closed loop of development —– they can design devices, grow the materials, fabricate the devices, and test and characterize them.” Krishna isn’t just waiting for industry to step in, he’s also busy transferring the technology he is researching into his own company, which he’s running with his wife. (See Taking a Clear Picture of Skin Cancer.)

Expanding Outreach

At the other end of the spectrum, Krishna dedicates his time to outreach efforts, connecting with students from elementary school to undergraduates in order to build their interest in engineering. “One of the biggest challenges the U.S. faces is the lack of next generation technology workforce,” explains Krishna. “Our outreach is designed to bring the excitement back into science.” He advises several student organizations at UNM, judges science fairs, mentors students, and encourages his students to do the same, saying, “The best way to learn is to teach.”

In 2005 Krishna extended his outreach efforts by starting Expand Your Engineering Skills (EYES), designed to increase the quality of students enrolling in Electrical and Computer Engineering graduate programs. EYES brings high-caliber international students to the ECE for a summer research program guided by a faculty advisor.

Engage –— Then Educate

Krishna is known at UNM for his engaging teaching style and dedication that extends well beyond the lecture hall. “Teaching is not restricted to the time you spend in the classroom,” he says. “It’s about hallway conversations, one-on-one meetings, and mentoring students.”

After considering his own educational experience and attending teaching seminars, Krishna created a student-centered, active learning approach, which combines short lectures, plenty of interaction, and actively gathering student feedback. He emphasizes group problem solving and semester-long group projects for undergraduates. He assigns students to groups, mixing their personalities, strengths, and weaknesses. “This simulates the industry environment,” he says. “When you work in industry you don’t have a choice of who you work with. Students can be very smart but the question is: ‘Can you work in a team and collaborate?’”

His enthusiasm for teaching and unique approach garnered Krishna several recent teaching awards, including the 2010 UNM Teacher of the Year Award and the 2009 Regents’ Lecturer Award. “It was a most rewarding experience to be the teacher of the year,” he says.

Chaouki Abdallah, chair of the department of electrical and computer engineering, nominated Krishna for the award. Abdallah sums up the spectrum of Krishna’s work at UNM saying, “Professor Krishna, while an excellent researcher, has also proven that he cares about undergraduate education and about mentoring graduate students,” explains Abdallah. “He continues to maintain an interest and involvement in teaching without sacrificing his research. He demonstrates the synergy of interdisciplinary research, teaching, outreach, and entrepreneurship. His career is a shining example for junior professors.”