Ferida Selim

Bowling Green State University, United States

Title: Advanced thermoluminescence spectroscopy as a research tool for semiconductor and photonic materials

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Biography

Farida Selim is a professor of Physics at the department of Physics and the Center for Photochemical Sciences at BGSU. She has a broad research program in the field of semiconductors and electronic and photonic materials; and has been active in constructing beam lines and developing new instrumentation for advanced material research. She authored 135 peer review journal articles, published two books, and numerous patents. She is on the advisory boards of six international scientific committees related to positron annihilation spectroscopy, oxide semiconductors, photonic materials, and radiation. She plays a leading role in national research projects including two new Energy Frontier Research Centers (EFRC) from Department of Energy

Abstract

Thermo-luminescence (TL) or thermally stimulated photoemission spectroscopy is based on liberating charge carriers from traps in the band gap by providing enough thermal energy to overcome the potential barrier of the traps. It provides a powerful tool to measure the positions of the localised states/traps in the band gap. Despite that, its applications in semiconductors have been very limited. 

Here  we describe the development of cryogenic thermally stimulated photoemission spectroscopy (C-TSPS) for the low temperature regime from 9 K to room temperature to extend TL  measurements to cover the entire range of shallow and deep levels in band gap materials  and show how it can be used for the characterisation of deep and shallow donors and acceptors in semiconductors. Examples of its applications in measuring/donor ionisation enegies in Ga₂O₃ and ZnO films and bulk crystals are demonstrated.   

This newly developed spectrometer provides a powerful characterisation tool for a wide range of semiconductors and electronic and photonic materials.   It can be used to measure the electrical transport properties of semiconductors and study exciton dynamics in photonic materials and reveal their interesting characteristics. It will advance material characterisation and development for a wide range of applications including lasers, electronic and illumination devices, and detectors for medical diagnostic and nuclear applications.