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Quantum Materials and Devices Seminars

Van der Waals Material Memory Devices and Advanced Ultrafast Imaging

Han Wang, University of Southern California

Wednesday, Sep 16, 2020
1:30 pm to 2:30 pm

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In this talk, I will discuss two separate topics of our recent study in van der Waals material based memory devices and new ultrafast imaging research, respectively. In the first part, our recent work in developing high performance ferroelectric tunneling junction based on the layered ferroelectric CuInP2S6 (CIPS) with asymmetric semi-metallic graphene and Cr contact. A record giant TER above 107 is obtained due to the large Fermi level shift in monolayer graphene in synergy with the flipping of the ferroelectric polarization in CIPS. The large Fermi level shift (barrier height modulation (BHM), ~1 eV) is attributed to the low density of states and quantum capacitance near the Dirac point of semi-metallic graphene. The vdW structure further enhances the TER due to the large carrier effective mass of the CIPS layer along its out-of-plane crystal direction. This new approach for achieving ultrahigh TER in FTJ memory based on atomically-thin semimetal graphene contact is also promising for high density integration with silicon electronics. In the second part of the talk, I will discuss our recent collaborative work reporting the first real-time spatial-temporal imaging of an optical chaotic system, which is of both fundamental scientific importance and practical relevance in key photonic applications such as laser optics and optical communication, by utilizing the recently developed compressed ultrafast photography. The time evolution of the system’s phase map is imaged at 100 billion frames per second without repeating measurement. We also demonstrate the ability to simultaneously control and monitor optical chaotic systems in real time. Our work introduces a new angle to the study of non-repeatable optical chaos completely different from the traditional time-averaged static imaging or spectral measurement, paving the way for fully understanding and utilizing chaotic systems in various disciplines.

Speaker Bio

Han Wang is an Associate Professor of Electrical and Computer Engineering and holder of the Robert G. and Mary G. Lane Early Career Chair at University of Southern California (USC). He received the B.A. degree in electrical and information science from Cambridge University in 2007 and his PhD degree from Massachusetts Institute of Technology (MIT) in 2013. From 2013 to 2014, he was with the Nanoscale Science and Technology group at IBM T. J. Watson Research Center. His research interests include the fundamental study and device innovation in electronics and photonics technology based on emerging nanomaterials for sensing, communication and computing applications. His work has been recognized with numerous awards including the Army Research Office Young Invesitgator Award, National Science Foundation CAREER award, IEEE Nanotechnology Council Early Career Award, the Roger A. Haken Best Paper Award in IEEE International Electron Device Meeting (IEDM), USC Viterbi Junior Faculty Research Award, and the MIT Jin-Au Kong Best Doctoral Thesis Award. He is the IEEE Nanotechnology Council Distinguished Lectuer for 2020-2021, and he is also recipient of the Orange County Engineering Council (OCEC) Outstanding Educator Award for his contributions to the science and engineering education in the Los Angeles area. Dr. Wang has authored or coauthored more than 100 publications in distinguished journals and conferences.


Emily Haderer