Out-of-Plane Resistance Switching of 2D Bi2O2Se at the Nanoscale

Two-dimensional (2D) bismuth oxyselenide (Bi2O2Se) with high electron mobility shows great potential for nanoelectronics. Although the in-plane properties of Bi2O2Se have been widely studied, its out-of-plane electrical transport behavior remains elusive, despite its importance in fabricating devices with new functionality and high integration density. Here, the out-of-plane electrical properties of 2D Bi2O2Se at nanoscale are revealed by conductive atomic force microscope. This work finds that hillocks with tunable heights and sizes are formed on Bi2O2Se after applying a vertical electric field. Intriguingly, such hillocks are conductive in the vertical direction, resulting in a previously unknown out-of-plane resistance switching in thick Bi2O2Se flakes while ohmic conductive characteristic in thin ones. Furthermore, the transformation is observed from bipolar to stable unipolar conduction in thick Bi2O2Se flake possessing such hillocks, suggesting its potential to function as a selector in vertical devices. This work reveals the unique out-of-plane transport behavior of 2D Bi2O2Se, providing the basis for fabricating vertical devices based on this emerging 2D material.

Automated summary

This study reveals the unique out-of-plane transport behavior of 2D Bi2O2Se, laying the foundation for fabricating vertical devices based on this emerging 2D material. Furthermore, it demonstrates the formation of conductive hillocks in Bi2O2Se under a vertical electric field, leading to out-of-plane resistance switching and potential applications as a selector in vertical devices.