In the past few decades, electronic devices have shrunk to miniature sizes, leading to more challenging operating environments in nanogaps. The electrical breakdown process is more complicated at smaller scales — interactions between the electric field and electrode materials dominate field emission behaviors and the breakdown. On the other hand, microplasmas generated by this electrical breakdown are useful in applications such as electric propulsion, nanomaterial synthesis, and medical treatment.

Understanding the mechanisms of electrical breakdown at the nanoscale is therefore important not only for the performance of electrical devices but also for microplasma applications. To this end, Li et al. conducted a comprehensive review of the field electron emission (FEE) process and vacuum breakdown in nanogaps.

“We have clarified crucial modeling and atomic simulation challenges by taking many related effects such as electrode morphology evolution and space-charge effect into account, as well as demonstrated cutting-edge experimental techniques to examine the nanoscale FEE and breakdown behaviors,” said author Guodong Meng.

The authors highlighted the state-of-the-art theories, experiments, and atomistics simulations relevant to the study of electron emission and electrical breakdown at the nanoscale. They hope their work can pave the way for building a nanogap that simultaneously addresses electron emission, nano-protrusion morphology evolution, and plasma formation.

“Substantial future studies on electrical breakdown at nanoscale are required,” said Meng. “To be specific, in-situ transmission electron microscopy is expected to be an important tool for discovering the complicated interaction between high electric fields and materials at the atomic scale.”

Source: “Review of electron emission and electrical breakdown in nanogaps,” by Yimeng Li, Lay Kee Ang, Bing Xiao, Flyura Djurabekova, Yonghong Cheng, and Guodong Meng, Physics of Plasmas (2024). The article can be accessed at https://doi.org/10.1063/5.0202607.