Browsing by Author "Chen, Jia"

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High-Precision Symmetric Weight Update of Memristor by Gate Voltage Ramping Method for Convolutional Neural Network Accelerator
(2020-03-01)
Chen, Jia
;
Pan, Wen-Qian
;
Li, Yi
;
Kuang, Rui
;
He, Yu-Hui
Memristor emerges as the key enabler for neural network accelerator. Here, we demonstrate high-precision symmetric weight update in a one transistor one resistor (1T1R) structure Ti/HfO2/TiN memristor using a gate voltage ramping method, with over 120-level states and low variation (< 4%). Incorporating all experimental non-idealities, the proposed mixed hardware-software convolutional neural network demonstrates over 92.79% online learning accuracy (against software equivalent 98.45%) for MNIST recognition task. The network also shows robustness to input image noises, array yield, and retention issues.
LiSiOX-Based Analog Memristive Synapse for Neuromorphic Computing
(2019-04-01)
Chen, Jia
;
Lin, Chih-Yang
;
Li, Yi
;
Qin, Chao
;
Lu, Ke
The progress in the neuromorphic computing hinges on the development of nanoscale analog artificial synapses. Here, we report a LiSiOX (LSO)-based memristive synapse with 100-level conductance states under identical pulses, representing synaptic potentiation and depression behaviors. The superior analog behaviors originate from the dynamic evolution of an electro-thermal modulation region with the motion of lithium and oxygen ions. A three-layer perceptron was constructed in simulation with LSO synapses, and a 91.97% recognition accuracy was achieved for handwritten digits. Moreover, the influences of several critical parameters, including device variability and weight precision, on the accuracy have been investigated. This letter provides guidelines for the optimization of synaptic device in robust memristive neural network.
The morphologies and fluorescence quantum yields of perylene diimide dye-doped PS and PHVB microspheres
(2018-01-01)
Chen, Jia
;
Jia, Shuoxun
;
Ji, Xiaohuan
;
Nourrein, Mohamed
;
Xiang, Hengxue
Aggregation and continuous -stacking have been the major obstacles hindering the fluorescence (FL) quantum yield (phi(F)) of perylene diimide (PDI) derivatives in the condensed phase. To prepare polymer microspheres with nearly unity phi(F), in this work a POSS functionalized PDI derivative, POSS-PDI-POSS (PPP), was applied as the red fluorophore of poly(3-hydroxylbutyrate-co-3-hydroxyvalerate) (PHBV) and polystyrene (PS) microspheres. The electrosprayed PPP/PHBV and PPP/PS microspheres have unique hollow structures. Moreover, they show bright red FL under a fluorescence microscope. A photophysical study of the microspheres indicates a significant role of the polymer matrix in disrupting the aggregation state and the phi(F) of the embedded PPP fluorophore. Both the PPP/PHBV and the PPP/PS microspheres show higher phi(F) than most PDI materials in the condensed phase. The PPP/PHBV microspheres show phi(F) of 28%, whereas the PPP/PS microspheres give nearly unity phi(F).