Augmentation of Room Temperature Gas Sensing Properties of Polymeric Porous Carbon Thin Films by Ar+ (100 Kev) Ion Irradiation

Abstract

Polymeric carbon thin films were deposited by the thermal evaporation technique from the polyaniline-based precursor prepared by chemical oxidation method. To enhance the sensing properties, deposited thin films were irradiated with four different concentrations (i.e. 1×1014, 1×1015, 1×1016 and 3×1016 ions/cm2) of Ar+ ions having energy 100 keV. Field emission scanning electron microscope (FESEM) images of un-irradiated and irradiated thin films indicate the agglomerated morphology of un-irradiated thin film, which is significantly changes with the irradiation dose. Raman spectra of irradiated thin films contains the required fundamental bands which confirms the deposition of expected polymeric carbon thin films. XRD patterns of as-deposited and Ar+ ion irradiated thin films are of semi-crystalline in nature. The energy band gap decreases from 3.59 to 2.24 eV as irradiation dose increases from 0 to 3×1016 ions/cm2­. The as-deposited polymeric carbon thin film exhibits the lowest values of sensing response (%) ~33%, whereas, the thin film irradiated with highest dose ~3×1016 ions/cm2­ exhibits highest sensing response (%) ~1119% at 100 ppm level of methanol vapors. Fabricated sensors are also highly stable and exhibited more than 85% sensing response (%) of initial response values even after 360 days.

Keywords: PANI, Ar+ ions, Irradiated, porous, Methanol