Field emission study from an array of hierarchical micro protrusions on stainless steel surface generated by femtosecond pulsed laser irradiation

摘要

This paper reports our results on femtosecond (fs) pulsed laser induced surface microano structuring of stainless steel 304 (SS 304) samples and their characterization in terms of surface morphology, formed material phases on laser irradiation and field emission studies. Our investigations reveal that nearly uniform and dense array of hierarchical micro-protrusions (density: similar to 5.6 x 10(5) protrusions/cm(2)) is formed upon laser treatment. Typical tip diameters of the generated protrusions are in the range of 2-5 mu m and these protrusions are covered with submicron sized features. Grazing incidence X-ray diffraction (GIXRD) analysis of the laser irradiated sample surface has shown formation mainly of iron oxides and cementite (Fe3C) phases in the treated region. These laser micro-structured samples have shown good field emission properties such as low turn on field (similar to 4.1V/mu m), high macroscopic field enhancement factor (1830) and stable field emission current under ultra high vacuum conditions. (C) 2016 Elsevier B.V. All rights reserved.