The Microscopic Origin of Efficiency Droop in LEDs
11-20-17
Marco Bernardi, Assistant Professor of Applied Physics and Materials Science, and his colleagues’ semiconductor research has shown that the coupling between electrons and thermal vibrations may be sapping energy from Light-emitting diodes—or LEDs. "Our work shows for the first time that the ever-present interaction between electrons with lattice vibrations can, by itself, explain why excited electrons can leak out of the active layer and account for inefficiencies in GaN LEDs," Professor Bernardi says. [Caltech story]
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Marco Bernardi
Professor Bernardi Wins AFOSR Young Investigator Award
10-11-17
Marco Bernardi, Assistant Professor of Applied Physics and Materials Science, has won a 2017 Air Force Office of Scientific Research (AFOSR) Young Investigator Award. The objectives of this program are: to foster creative basic research in science and engineering, enhance early career development of outstanding young investigators, and increase opportunities for the young investigators to recognize the Air Force mission and the related challenges in science and engineering. Professor Bernardi received the award for his proposal entitled, “Ab Initio Electron-Defect and Electron-Phonon Scattering for Understanding and Designing High-Mobility Semiconductors and Oxides.” [AFOSR Press Release]
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Marco Bernardi
"Hot" Electrons Move Faster Than Expected
06-15-17
For the first time, Marco Bernardi, Assistant Professor of Applied Physics and Materials Science, and colleagues have been able to directly observe the ultrafast motion of electrons immediately after they are excited with a laser—and found that these electrons diffuse into their surroundings much faster and farther than previously expected. "Our work shows the existence of a fast transient that lasts for a few hundred picoseconds, during which electrons move much faster than their room-temperature speed, implying that they can cover longer distances in a given time when manipulated with lasers," says Professor Bernardi. "This non-equilibrium behavior could be employed in novel electronic, optoelectronic, and renewable energy devices, as well as to uncover new fundamental physics." [Caltech story]
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Marco Bernardi