Grad student honored with NASA Space Technology Research Fellowship

ECE ILLINOIS graduate student Dicky Liu is going to pass on an NSF Graduate Research Fellowship this year. While he was honored to be among the three ECE students who were offered a place in one of the nation’s oldest and most prestigious programs, he has decided to decline in favor of a different honor, a NASA Space Technology Research Fellowship.

“I chose to go with NASA [because of] the mentorship and the visiting technologist experience," he said. "I will spend ten weeks every year at a NASA center conducting my research with the help from experts in the field. In addition, I will be assigned a personal research advisor from NASA to help coach me in my endeavors.” At Illinois, he is an MNTL affiliate and advised by ECE Professor Can Bayram.

His research interests will align well with NASA’s initiatives. As he explained, ultraviolet (UV) radiation has shown important applications in space technology including gravitational wave observation, light detection and ranging, planetary atmospheric measurements, and chemical spectroscopy.

“Laser diodes have many advantages over other forms of lasers, offering extremely compact, inexpensive and simple designs that can achieve high power, efficiency, gain, and modulation speed while maintaining an excellent reliability and longevity,” he said. For this reason, they have become the preferred choice for NASA. Currently, UV emitters are based on semiconductors that have properties such as: polarizations, poor facet mirrors and low hole mobility, that are detrimental for the performance UV lasers.

His fellowship proposal seeks to resolve the unsatisfactory performance of the laser. Gallium Nitride (GaN) can be engineered in its metastable cubic phase to display superior properties. The use of such a method would result in a polarization-free semiconductor with high quality mirrors for the laser. While applying, he worked with the Graduate College Office of External Fellowships.

Comprehensively, metalorganic chemical vapor deposition (MOCVD) is a technique that turns gases into a solid thin-film semiconductor. Liu has suggested growing the cubic phase of GaN via MOCVD on carefully patterned Si (100). This will resolve problems such as phase mixing or defects presented by conventional approaches. Moreover, numerous benefits include the inexpensiveness of the substrate, scalability, and ability to integrate with Si devices. 

“This proposal opens up a path to polarization-free III-Nitride laser diodes for space applications,” he said. “I am very excited about the once-in-a-lifetime opportunity to facilitate collaboration between ECE and NASA.”