title: Very stable electron field emission from strontium titanate coated carbon nanotube matrices with low emission thresholds.
abstract: Novel PMMA-STO-CNT matrices were created by opened-tip vertically aligned multiwalled carbon nanotubes (VA-MWCNTs) with conformal coatings of strontium titanate (STO) and poly(methyl methacrylate) (PMMA). Emission threshold of 0.8 V/μm was demonstrated, about 5-fold lower than that of the as-grown VA-MWCNTs. This was obtained after considering the related band structures under the perspective of work functions and tunneling width as a function of the STO thickness. We showed that there is an optimum thickness of STO coatings to effectively reduce the work function of CNTs and yet minimize the tunneling width for electron emissions. Furthermore, simulation and modeling suggest that PMMA-STO-CNT matrices have suppressed screening effects and Coulombs' repulsion forces between electrons in adjacent CNTs, leading to low emission threshold, high emission density, and prolonged emission stability. These findings are important for practical application of VA-MWCNTs in field emission devices, X-ray generation, and wave amplification.
authors.affiliation: Department of Physics, Michigan Technological University, 118 Fisher Hall, 1400 Townsend Drive, Houghton, Michigan 49931, USA.
authors.forename: Archana
authors.initials: A
authors.lastname: Pandey
authors.forename: Abhishek
authors.initials: A
authors.lastname: Prasad
authors.forename: Jason P
authors.initials: JP
authors.lastname: Moscatello
authors.forename: Mark
authors.initials: M
authors.lastname: Engelhard
authors.forename: Chongmin
authors.initials: C
authors.lastname: Wang
authors.forename: Yoke Khin
authors.initials: YK
authors.lastname: Yap
mesh_terms: D000327:Adsorption; D003198:Computer Simulation; D004579:Electron Transport; D004583:Electrons; D008422:Materials Testing; D008956:Models, Chemical; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure*; D010087:Oxides / Q000737:chemistry*; D010316:Particle Size; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D013324:Strontium / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*
chemical_list: D037742:Nanotubes, Carbon; D010087:Oxides; D019904:Polymethyl Methacrylate; D014025:Titanium; C119252:strontium titanium oxide; D013324:Strontium