April 22, 2022
@
11:00 am
–
12:00 pm
Pegah Bagheri, MSE Ph.D. Candidate
Pegah Bagheri, NC State MSE Ph.D. Candidate
Talk Point Defect Management in Ultrawide Bandgap Materials
Abstract
The AlGaN material system is a class of ultra-wide bandgap semiconductors with a tunable, direct bandgap from 3.4 eV (GaN) to 6.1 eV (AlN) making it the most promising candidate for a range of high-frequency high-power electronic and deep-ultraviolet optoelectronic applications. These include efficient energy conversion, sensing, disinfection, healthcare, communication, etc. The commercialization of AlGaN-based devices, however, has been precluded due to the significant challenges associated with efficient n- and p-type doping at high and low levels owing to the formation of compensating point defects and complexes during the epitaxial growth. For instance, at high doping levels (injection layers in optoelectronics) AlGaN exhibits a “knee behavior” limiting the maximum achievable carrier concentrations in n- and p-type AlGaN. Similarly, at low doping levels (drift layers in power electronics) a low doping limit exists in AlGaN limiting the minimum achievable carrier concentration while retaining large mobility. Furthermore, the donors undergo a deep level transition in Al-rich AlGaN and AlN making it extremely challenging to realize low resistivity in these materials. The successful implementation of the AlGaN technology thus necessitates the development of systematic point defect management strategies. Defect management toolboxes such as Chemical Potential Control (CPC) and Defect Quasi Fermi Level (dQFL) control techniques can be used to manage point defects and realize state-of-the-art conductivity in Al-rich AlGaN and AlN.
Biography
Pegah Bagheri is PhD candidate in the Department of Materials Science and Engineering (MSE) at North Carolina State University (NCSU), researching on the growth and characterization of wide bandgap semiconductor thin films for optoelectronics, power electronics and quantum photonic applications. She received his B.S. in Materials Science and Engineering and minor in Physics from Sharif University of Technology in 2016, in Tehran and Masters in MSE at NCSU in 2021. Her current research involves the development of systematic framework to manage point defects formation in III-N semiconductors to control their optical, electrical, and structural properties for optoelectronics, power electronics and quantum photonic applications. She has published over 18 research articles in refereed journals and had numerous presentations at national conferences.
