Authors: S A Jalil S Bashir M Akram Q S Ahmed F U Haq
Publish Date: 2017/03/02
Volume: 91, Issue: 8, Pages: 953-965
Abstract
The effect of laser fluence on the surface morphology and field emission properties of nickel Ni has been investigated Circular shaped Ni targets are irradiated with NdYAG laser 1064 nm 10 Hz 10 ns at various fluences ranging from 52 to 26 J/cm2 in air For low fluence ranging from 52 to 104 J/cm2 SEM analysis reveals the growth of unorganized channels grains droplets and ridges Whereas at moderate fluence of 156 J/cm2 the formation of ridges and cones along with few number of holes are observed However at high fluence regime ranging from 20 to 26 J/cm2 a sharp transition in morphology from ridges to holes has been observed The laser structured Ni targets are also investigated for field emission properties by recording their I–V characteristics and Fowler–Nordheim F–N plots The enhancement in field emission factor β and the reduction in turn on field are found to be dependent upon the laser fluence and morphology of the grown structures For samples treated at low and moderate fluences the growth of cones channels and ridges is responsible for enhancement of β factor ranging from 121 to 178 Whereas for samples treated at high fluence region the formation of pores and holes is responsible for significant field convergence and consequently resulting in substantial enhancement in β factor to 276
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