Electron field emission from polymer films treated by a pulsed ultraviolet laser

The poly(phenylcarbyne) polymer films were coated on silicon substrates and then irradiated by a pulsed ultraviolet laser (λ = 248 nm) with various fluences (1-60 mJ/cm²) at an atmospheric pressure of nitrogen. The structures of the resulted films were investigated by Raman spectroscopy. The morphologies of the films were examined by scanning electron microscopy (SEM). The electron field emission properties of the films as cathodes were studied. Raman spectrum analysis and SEM results indicate that the polymer film is converted to nanoparticle carbon film with the laser fluence from 10 to 60 mJ/cm². The conversion mechanism from the polymer to nanoparticle carbon and electron field emission mechanism from the converted carbon film is discussed. The converted carbon film showed better field emission properties, i.e., lower turn-on threshold emission field, higher emission current density, and higher emission light spot density with increasing laser fluence from 10 to 50 mJ/cm². By increasing the laser fluence from 50 to 60 mJ/cm², the emission property showed a slight degradation. A turn-on threshold emission field of 1.8 V/μm (at 1 nA/cm²) and emission current density of 30 mA/cm² with an emission light spot density of 10⁴/cm² (at 14 V/μm) were observed for the polymer film irradiated with a fluence of 50 mJ/cm². Circular and multiple-line field emission patterns are demonstrated using the laser irradiation of the poly(phenylcarbyne) polymer.