Lee's student wins prize at major MBE conference
ECE Associate Professor Minjoo Larry Lee’s student Michelle Vaisman won a best student presentation award at the 2016 North American Molecular Beam Epitaxy (NAMBE) conference in September. This award is the eighth best student presentation or poster award for Lee’s research group.
Vaisman, who is finishing her doctorate at Yale, received the prize for work that achieved record-setting efficiency for solar cells grown by molecular beam epitaxy. Her approach was to integrate a new III-V device architecture made from gallium arsenide phosphide onto a conventional silicon wafer.
“Michelle was able to improve both the material quality and device design for GaAsP on Si solar cells, resulting in increased voltage and current output, respectively,” explained Lee. “A detailed understanding of how defects nucleate during III-V growth on Si led us to new strategies for how to minimize their formation.”
Vaisman’s new solar cells recently achieved 15 percent efficiency, which surpasses the previous record of 9.8 percent efficiency for GaAsP-on-silicon solar cells. According to Lee, Vaisman’s work significantly advanced the current state of GaAsP/GaP/Si solar cells and has established a realistic path toward a new class of solar cells capable of reaching 30 percent efficiency—commercially available silicon-only solar cells are capable of reaching 26 percent efficiency.
Vaisman’s co-authors on this work included Kevin Nay Yaung and Emmett Perl.
Illinois and the NAMBE conference
In its 32nd year, the NAMBE conference is the preeminent international forum for reporting scientific and technology developments around molecular beam epitaxy crystal growth.
New ECE and MNTL faculty member Larry Lee won the NAMBE Young Investigator Award in 2012 for outstanding contributions to the growth of III-phosphide materials and devices by solid-source MBE. Already a dominant technology for wireless communication, high-brightness LEDs, and high-efficiency solar cells for space applications, III-phosphide compound semiconductors are a promising material for making highly efficient multi-junction solar cells.
In 2007, then-MNTL Professor K.Y. Norman Cheng received the MBE Innovator Award at the conference for developing InGaAs-based heterostructures for ultra-high-speed devices, for pioneering work in III-V dilute nitride semiconductor alloys, and for inventing the rotating substrate holder used in MBE systems. Early in his career, Cheng worked with MBE inventor and ECE Illinois alumnus Al Cho (PhD 1968) at Bell Labs—Cho, incidentally, was the founder of the NAMBE conference.