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SIGS researchers find the out-of-plane unipolar resistive switching in 2D Bi2O2Se at the nanoscale

        Two-dimensional (2D) semiconducting bismuth oxyselenide (Bi2O2Se) has been widely used in photodetectors, sensors, and RRAMs due to its high stability and decent mobility. However, almost all these devices are based on in-plane carrier transport at the microscale. At the nanoscale, the electrical properties of 2D materials play an important role in the performance and/or mechanism of related microscopic or macroscopic electronic devices.

Recently, Prof. Bilu Liu’s research team from Tsinghua Shenzhen International Graduate School reported unique out-of-plane resistive switching in nanoscale 2D Bi2O2Se by conductive atomic force microscopy (CAFM) technique. They found that hillocks, which make the Bi2O2Se become conductive, are formed on Bi2O2Se after applying a vertical electrical field. The height and width of hillocks can be controlled by changing the amplitude and sweeping cycles of the input vertical electrical field. Intriguingly, thick Bi2O2Se flakes show resistive switching behavior while thin Bi2O2Se flakes show ohmic conductive behavior. The researchers also observed the transformation from bipolar to stable unipolar conduction in thick Bi2O2Se flakes possessing such hillocks. This work reveals unique nanoscale out-of-plane transport behavior in 2D Bi2O2Se, providing additional direction for fabricating vertical devices based on this emerging 2D material.

The formation of hillock on Bi2O2Se flakes after the application of vertical electrical field.

The transformation from bipolar to stable unipolar conduction in thick Bi2O2Se flakes.

Wenjun Chen, Rongjie Zhang, Rongxu Zheng, Bilu Liu. Out-of-Plane Resistance Switching of 2D Bi2O2Se at the Nanoscale. 2021, DOI:10.1002/adfm.202105795.

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Writer: Rongjie Zhang

Pictures: Wenjun Chen