Kinetic Characterisation of Electron Transport Swarms and Dissociation Kinetics in Ammonia-Hydrogen Plasmas

International Journal of Physics | Vol. 12, No. 1, January 2021 | pp. 1–8

DOI: 10.46882/2021/IJP/000129

Research Article

Title: Kinetic Characterisation of Electron Transport Swarms and Dissociation Kinetics in Ammonia-Hydrogen Plasmas

Names of Authors: D. L. Santos¹, S. H. Zhang²

Authors’ Affiliations:
¹ Department of Physics, University of Coimbra, Coimbra, Portugal
² Department of Physics, Tsinghua University, Beijing, China

Abstract: Ammonia-hydrogen (NH3-H2) gas mixtures are heavily utilized across the metallurgical processing and microelectronics manufacturing sectors for nitride passivation, steel hardening, and high-purity semiconductor crystal deposition. This paper presents a self-consistent kinetic characterisation of electron transport swarms and evaluates molecular dissociation paths in low-pressure ammonia-hydrogen discharges. We calculated solution profiles for the electron Boltzmann equation using a multi-term spherical harmonic expansion engine across an expansive reduced electric field range (E/N) spanning 5.0 Td to 600.0 Td. The cross-section matrix items detailed elastic momentum shifts, rotational transitions, vibrational pumping, dissociative attachment, and direct electronic impact ionization events. The calculations reveal that adding small ammonia quantities (from 2.0% to 15.0% by volume) strongly skews the high-energy profile of the electron energy distribution function. At a marker of E/N = 50.0 Td, the total amidogen (NH2) radical generation rate coefficient scales up by an order of magnitude, driven by intense energy confinement near the primary vibrational impact boundaries. The simulated drift velocity constants match independent experiment recordings within a minor ±4.8% variation.

Keywords: Ammonia plasmas; Boltzmann equation; electron transport; dissociation kinetics; plasma processing; cross-section

Manuscript Timeline: Received: October 12, 2020; Revised: November 24, 2020; Accepted: December 15, 2020; Published: January 14, 2021

Citation: Santos, D. L., & Zhang, S. H. (2021). Kinetic Characterisation of Electron Transport Swarms and Dissociation Kinetics in Ammonia-Hydrogen Plasmas. International Journal of Physics, 12(1), 1–8.

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