Andriy Lotnyk1,2,3,Hagen Bryja1,Jürgen Gerlach1
Leibniz Institute of Surface Engineering1,Research Institute of Advanced Technologies, Ningbo University2,College of Physics and Optoelectronic Engineering, Harbin Engineering University3
Andriy Lotnyk1,2,3,Hagen Bryja1,Jürgen Gerlach1
Leibniz Institute of Surface Engineering1,Research Institute of Advanced Technologies, Ningbo University2,College of Physics and Optoelectronic Engineering, Harbin Engineering University3
Chalcogenide-based phase change alloys are promising materials for optical and electronic memory applications. In this work, we propose to use epitaxial layered 2D-like Sb<sub>2</sub>Te<sub>3</sub> thin films for memory and neuromorphic applications [1]. High-quality Sb<sub>2</sub>Te<sub>3</sub> thin films were directly deposited on microelectronics-relevant Si(111) substrates by pulsed laser deposition (PLD) using low deposition temperature of 200°C. This offers an industry applicable large-scale method for the fabrication of memory devices, circumventing major challenges in the integration of 2D-like materials. Different top electrode metals were utilized to prepare vertical memory device structures.<br/><br/>The switching characteristics of Sb<sub>2</sub>Te<sub>3</sub> -based cells were dependent on the used top electrode metals. The use of Ag and Cu electrodes showed pronounced bipolar memristive switching of memory devices. The devices utilizing Ag top electrode revealed analog programmability, stable multilevel retention, and endurance performance with a memory window larger than one order of magnitude. However, memory devices based on Cu top electrodes led to a memristive switching with smaller memory window and volatility of programmed states. In addition, memory devices with Cu and Ag top electrodes offer forming-free operation and self-compliance. Moreover, detailed structural and chemical characterization indicated diffusion of Ag and Cu into the Sb<sub>2</sub>Te<sub>3</sub> thin films, suggesting that charge trapping is involved in the memristive switching mechanism. Overall, this work shows the high potential of epitaxial layered Sb<sub>2</sub>Te<sub>3</sub> thin films for non-volatile memory applications, including neuromorphic computing.<br/><br/>Acknowledgements<br/>The authors would like to thank A. Mill for TEM specimen preparation, P. Hertel for deposition of metal contacts, M. Ehrhardt for laser cutting of shadow masks and A. Prager for XPS measurements. We acknowledge the support by the Free State of Saxony within the project ‘Switching with light’.<br/><br/>References<br/>[1] H. Bryja, J.W. Gerlach, A. Prager, M. Ehrhardt, B. Rauschenbach, A Lotnyk, 2D Materials 8 (2021) 045027