Analytical electron emission scaling laws for cathode: 2D materials and surface roughness by fractional modelling

LAY KEE ANG^1*

¹Science, Mathematics and Technology, Singapore University of Technology and Design, Singapore, Singapore

* Presenter:LAY KEE ANG, email:ricky_ang@sutd.edu.sg

Electron emission from a material through an interface to vacuum or into other material is a fundamental process in plasma, cathode, gas ionization, and electrical contact. Depending on the energy used to produce electron emission, it can be broadly characterized into 3 processes: thermionic emission TE (thermal energy), field emission FE (quantum tunneling) and photoemission PE (photon absorption or optical tunneling). Regardless of the emission mechanism, the emission current density may become saturated – space charge limited emission (SCLE). Basic models for these processes (TE, PE, PE, SCLE) have been captured in the Richardson law, Child-Langmuir (CL) law, Fowler-Nordheim (FN) law, and the Keldysh model. With the development of two-dimensional (2D) atomic scale materials, these classical laws may require revision to account for new material properties. For practical cathodes, the effects of roughness cannot be ignored. To include such roughness, fractional calculus techniques can be used to model it by using a parameter to describe the roughness as an object with fractional dimensions. In this talke, we will present the recent analytical emission models to account for 2D materials and roughness that are absent from the traditional models. New scaling laws will be reported different from the traditional understandings.

Keywords: non-neutral plasmas, plasma discharge, electron emission, theory, modeling