| AVS 65th International Symposium & Exhibition | |
| Reconfigurable Materials and Devices for Neuromorphic Computing Focus Topic | Tuesday Sessions |
| Session RM-TuP |
| Session: | Reconfigurable Materials and Devices for Neuromorphic Computing Poster Session |
| Presenter: | Yong Kim, Seoul National University of Science and Technology, Republic of Korea |
| Authors: | Y. Kim, Seoul National University of Science and Technology, Republic of Korea S.Y. Ryu, Seoul National University of Science and Technology, Republic of Korea W.H. Jeong, Seoul National University of Science and Technology, Republic of Korea K.-S. Min, Kookmin University, Republic of Korea B.J. Choi, Seoul National University of Science and Technology, Republic of Korea |
| Correspondent: | Click to Email |
DRAM and flash memory currently being used as working memory devices must be configured with transistors. For this reason, it has been reached the limits of scaling, power consumption and fabrication cost. In order to overcome these limits, next-generation memory devices have been developed and materials/device structures have been studied actively. Memristor could be used as a nonvolatile memory with simple crossbar array (CBA) structure. Although CBA structure is possible to innovatively overcome the scaling limits, it has major problem, so called sneak path current. It is caused by cross talking near the selected cell and typically solved by adding an additional selector device (e.g., diode, transistor, etc.). Recently, self-rectifying memristor could be enabled by bilayer stack, which could much simplifying the CBA structure: selector-less CBA. We fabricated the 10x10 and 30x30 CBA as selector-less memristor device using the potential barrier between each stack of the fabricated MIM structure.
In this study, we have acquired the self-rectifying characteristics for CBA structure using the Pt/HfO2/Ti device. The device was fabricated 10x10 and 30x30 CBA patterned with 2 – 20 μm of electrode size. The top/bottom electrodes were deposited using electron beam evaporator and the dielectric material was deposited by atomic layer deposition (ALD). HfO2 layer grown by ALD plays the role of switching layer in memristor. The thickness of the switching layer was quite thin, which eliminates the need for electroforming process. In addition, we obtained the self-rectifying characteristic that does not permit the fluent current conduction under negative bias through the potential barrier between Pt and HfO2 layer.
As a result of electrical properties, this device follows an interface-type switching mechanism in which the current value decreased as the electrode size decreased. By inserting Al2O3 layer of 1 - 2nm, it was confirmed that switching occurs in HfO2/Ti interface. The size of the formed conductive region was changed through the positive bias and the stability of the rectifying function was verified by applying the negative bias up to -3V. We confirmed the uniformity of memristor cells randomly chosen among 10x10 and 30x30 CBA and verified the device-to-device variability. Cycle-to-cycle variability was also obtained from these cells through a switching of more than 100 cycles. Finally, the AC measurement was applied to explore the possibility of fabricated device as a synaptic device.