Topic: Electronic Trap Detection with Carrier-Resolved Photo-Hall Effect

Lecturer: Byungha Shin, Fellow of Korea Academy of Science and Technology

Time: January 12th, 2026, 15:00, UTC+8

Venue: Room 301, State Key Laboratory of Advanced Technology For Materials Synthesis and Processing

Biography: Byungha Shin is Professor in the Department of Materials Science and Engineering (MSE), at Korea Advanced Institute of Science and Technology (KAIST) in Daejeon, Korea. His past research experience includes the study of thin film growth kinetics and high-k dielectric materials for microelectronic applications. His current primary research interest is developing novel materials for energy applications with the current emphasis on hybrid perovskite optoelectronic devices (PV, LED, and radiation-detector), chalcogenide thin film solar cells, and photoelectrochemical water splitting and electrochemical nitrogen reduction. He has published over 130 SCI journal papers, including Science (2020) and Nature (2019), and he has given over 100 invited talks at various academic institutes and international conferences. He was a recipient of “Scientist of the Month” and “100 Outstanding Research Achievements”, both by Ministry of Science and ICT of Korean Government in 2021, “The 2020 KAISTian of the Year Award” by KAIST in 2020, and “KAIST’s Top 10 Research Achievements of 2019” by KAIST in 2019. In 2025, he was elected as a Fellow of The Korea Academy of Science and Technology.

Abstract: Electronic trap states are a critical yet unavoidable aspect of semiconductor devices, 20 impacting performance of various electronic devices such as transistors, memory devices, solar cells, and LEDs. The density, energy level, and position of these trap states often enable or constrain device functionality, making their measurement crucial in materials science and device fabrication. Most methods for measuring trap states involve fabricating a junction, which can inadvertently introduce or alter traps, highlighting the need for 25 alternative, less-invasive techniques. Here, we present a unique photo-Hall-based method to detect and characterize trap density and energy level while concurrently extracting key carrier properties, including mobility, photocarrier density, recombination lifetime, and diffusion length. This technique relies on analyzing the photo-Hall data in terms of “photo-Hall conductivity” vs. electrical conductivity under varying light intensities and 30 temperatures. We show that the photo-Hall effect, in the presence of traps, follows an astonishingly simple relationship, a hyperbola equation, that reveals detailed insights into charge transport and trap occupation. We have successfully applied this technique to P and N-type silicon as a benchmark and to high-performance halide perovskite photovoltaic films. This technique substantially expands the capability of Hall effect-based 35 measurements by integrating the effects of the four most common excitations in nature - electric field, magnetic field, photon, and phonon in solids - into a single equation and enabling unparalleled extraction of charge carrier and trap properties in semiconductors.

Rewritten by: Mei Mengqi

Edited by: Liang Muwei, Li Huihui, Li Tiantian

Source: State Key Laboratory of Advanced Technology For Materials Synthesis and Processing