posted on 2020-02-20, 19:47authored bySourav Roy, Gang Niu, Qiang Wang, Yankun Wang, Yijun Zhang, Heping Wu, Shijie Zhai, Peng Shi, Sannian Song, Zhitang Song, Zuo-Guang Ye, Christian Wenger, Thomas Schroeder, Ya-Hong Xie, Xiangjian Meng, Wenbo Luo, Wei Ren
The
potential in a synaptic simulation for neuromorphic computation
has revived the research interest of resistive random access memory
(RRAM). However, novel applications require reliable multilevel resistive
switching (RS), which still represents a challenge. We demonstrate
in this work the achievement of reliable HfO2-based RRAM
devices for synaptic simulation by performing the Al doping and the
postdeposition annealing (PDA). Transmission electron microscopy and
operando hard X-ray photoelectron spectroscopy results reveal the
positive impact of Al doping on the formation of oxygen vacancies.
Detailed I–V characterizations
demonstrate that the 16.5% Al doping concentration leads to better
RS properties of the device. In comparison with the other reported
results based on HfO2 RRAM, our devices with 16.5% Al-doping
and PDA at 450 °C show better reliable multilevel RS (∼20
levels) performance and an increased on/off ratio. The 16.5% Al:HfO2 sample with PDA at 450 °C shows good potentiation/depression
characteristics with low pulse width (10 μs) along with a good
On/Off ratio (>1000), good data retention at room temperature,
and
high temperature and good program/erase endurance characteristics
with a pulse width of 50 ns. The synapse features including potentiation,
depression, and spike time-dependent plasticity were successfully
achieved using optimized Al-HfO2 RRAM devices. Our results
demonstrate the beneficial effects of Al doping and PDA on the enhancement
of the performances of RRAM devices for the synaptic simulation in
neuromorphic computing applications.