Sub-ps Laser Deposited Copper Films for Application in RF Guns

Antonella Lorusso; Zsolt Kovács; Barnabás Gilicze; Sándor Szatmári; Alessio Perrone; Tamás Szörényi

doi:10.3390/ma16031267

Sub-ps Laser Deposited Copper Films for Application in RF Guns

Materials (Basel). 2023 Feb 2;16(3):1267. doi: 10.3390/ma16031267.

Authors

Antonella Lorusso¹, Zsolt Kovács², Barnabás Gilicze³, Sándor Szatmári³, Alessio Perrone¹, Tamás Szörényi⁴

Affiliations

¹ Department of Mathematics and Physics "E. De Giorgi", University of Salento and National Institute of Nuclear Physics, 73100 Lecce, Italy.
² Department of High Energy Experimental Particle and Heavy Ion Physics, Wigner Research Centre for Physics, H-1121 Budapest, Hungary.
³ Institute of Physics, University of Szeged, H-6720 Szeged, Hungary.
⁴ Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Hungary.

Abstract

Copper thin films are intended to serve as a cover layer of photocathodes that are deposited by ablating copper targets in a high vacuum by temporally clean 600 fs laser pulses at 248 nm. The extremely forward-peaked plume produced by the ultrashort UV pulses of high-energy contrast ensures fast film growth. The deposition rate, defined as peak thickness per number of pulses, rises from 0.03 to 0.11 nm/pulse with an increasing ablated area while keeping the pulse energy constant. The material distribution over the surface-to-be-coated can also effectively be controlled by tuning the dimensions of the ablated area: surface patterning from airbrush-like to broad strokes is available. The well-adhering films of uniform surface morphology consist of densely packed lentil-like particles of several hundred nm in diameter and several ten nm in height. Task-optimized ultrashort UV laser deposition is thereby an effective approach for the production of thin film patterns of predetermined geometry, serving e.g., as critical parts of photocathodes.

Keywords: copper thin films; sub-ps laser ablation; ultrashort pulsed laser deposition.

Grants and funding

This work was supported by the Italian National Institute of Nuclear Physics (INFN), the European Union’s Horizon 2020 research and innovation programme at Laserlab-Europe (grant agreement #654148, Access Programme project DP-USZ002584), and the European Social Fund EFOP-3.6.2-16-2017-00005 “Ultrafast physical processes in atoms, molecules, nanostructures and biological systems”. The project also received funding from the National Research, Development, and Innovation Office (OTKA K138339 project) of Hungary.