Carrier- and Trap-Resolved Photo-Hall Effect: Unlocking the 145-Year-Old Secret in Hall Effect
This seminar introduces the "carrier and trap resolved photo-Hall effect," a novel technique extending the classic Hall effect via a simple hyperbola equation to reveal majority/minority carrier properties and trap dynamics, unifying multiple physical excitations for enhanced semiconductor characterization.
Overview
We present exciting new discoveries of equations and a technique called “carrier and trap resolved photo-Hall effect”, that extends the classical Hall effect to reveal both majority and minority carrier properties, as well as trap dynamics*. While the Hall effect has driven fundamental advances in physics, including the quantum Hall effects, it traditionally provides only majority carrier information (type, density and mobility). We show that, in the presence of traps, the photo-Hall effect follows an astonishingly simple hyperbola equation, offering deep insights into charge transport and trap occupation. The technique is also applied to perovskite and silicon as a benchmark. This method unifies the effect of electric, magnetic, photon, and phonon excitations into a single equation, enables unparalleled semiconductor characterization capabilities and serves as a fascinating new example of unification idea in physics.
Presenters
Oki Gunawan, Research Staff Member, IBM Research, USA
Brief Biography
Oki Gunawan received his Ph.D. from Princeton University (2007) and his M.Eng. (2000) and B.Eng. (1998) from Nanyang Technological University, all in Electrical Engineering. He is currently a Research Staff Member at IBM Thomas J. Watson Research Center in Yorktown Heights, NY. His research interests include semiconductor physics and technology, valleytronics, electrodynamics, and photovoltaics. At IBM, he managed a photovoltaic characterization laboratory and led efforts to develop new systems and patents for advanced semiconductor characterization. An example of his invention is the IBM Parallel Dipole Line (PDL) Hall system, a high-sensitivity Hall system that played a key role in the discovery of the "Carrier-Resolved Photo Hall Effect," published in Nature (2019). He has authored more than 60 publications and 120 granted patents, some have been licensed for commercialization such as the “PDL Hall System”, manufactured by SEMILAB. He received the IBM Pat Goldberg Best Paper Award (2020) and the IBM Master Inventor Award (2024) for his contributions.
