Field emission study from tantalum surfaces micro-structured with femtosecond pulsed laser irradiation

Abstract

This paper presents our results on surface micro-structuring of tantalum samples using femtosecond (fs) pulsed laser irradiation and its effect on field emission performance. Micro-structuring of Ta targets has been carried by varying laser fluence in the range 0.35–0.55 J/cm2 while keeping target scan speed constant at 25 µm/s. Laser-treated surfaces have shown the formation of high density micro-protrusions and an oxide phase mainly consisting of crystalline Ta2O5. Our results showed substantial improvement in field emission performance of laser micro-structured surfaces in comparison to pristine Ta surface. Areal number density of micro-protrusions decreases from 8.8 × 105 to 3.5 × 105 protrusions/cm2 as incident laser fluence varied from 0.35 to 0.55 J/cm2. Ta sample micro-structured with 0.55 J/cm2 laser fluence has shown low turn on field (~ 4.0 ± 0.6 Vµm− 1) and high-field enhancement factor (4500 ± 500).