题 目：Analog synapse devices based on interface resistive switching for neuromorphic system
报告人：Hyunsang Hwang 教授 韩国浦项科技大学 (POSTECH)
Hardware artificial neural network (ANN) system with high density synapse and neuron can perform massive parallel computing which is effective for pattern recognition and clustering of unstructured data. To implement neuromorphic system, we need to develop ideal synapse device with various requirements such as scalability, MLC characteristics, low power operation, data retention, and symmetric potentiation/depression characteristics. Although various devices such as filamentary ReRAM, PRAM, and MRAM were proposed for synapse applications, these devices cannot meet the requirements of synapse device. Using redox reaction at metal/oxide interface, we developed analog synapse device. Compared with filament switching device which has intrinsic variability of switching parameters, interface resistive switching device exhibits excellent switching uniformity and area scalability. By controlling the reactivity of metal electrode and oxygen concentration in oxide, we can modulate conductance under potentiation and depression conditions. We have fabricated wafer-scale high density synapse array device with excellent switching uniformity. By modulating the linearity and symmetry of conductance change, we have estimated the accuracy of pattern recognition of handwritten digits. We found that synapse device with linear and symmetric conductance change exhibits improved pattern recognition accuracy.
Hyunsang Hwang is a professor in Pohang University of Science and Technology, department of Materials science and Engineering. In 1992, he graduated in Materials Science and Engineering from University of Texas at Austin. He worked as Principal Research Engineer, LG Semiconductor Company, Korea from 1992 to 1997. In 1997 he was appointed as a professor in Dept. of MSE, GIST, during this period, he worked as Visiting Research Professor in Department of Electrical Engineering in Stanford University, USA（2007~2008）and Oak Ridge National Lab., USA in 2002. In 2012 he leaved for Department of MSE in POSTECH as a professor. Until now, he has cultivated 23 Ph.D and 54 Master students, and 14 of them got the best student paper awards. He is author of about 330 journal papers and inventor of 55 international patents. During his career he has given 35 invited presentations, plenary talks and tutorial lectures. He is a Senior Member of IEEE Electron Device Society. He has been member of committees on important conferences such as IEEE International Electron Device Meeting (Memory Technology Program committee 2009, 2010), IEEE Semiconductor Interface Specialists Conf., (Technical Program Committee 2008, 2009, 2010) and International Conf. on Solid State Devices and Materials (program committee 2005-2008, 2011-2014). He also served as Technical Program Co-chair (2012) and Technical Program Vice-chair (2011) of Korean Conference on Semiconductors (KCS) and Chair of Thin Film committee (2009-2011).