title: Vertically-Aligned Single-Crystal Nanocone Arrays: Controlled Fabrication and Enhanced Field Emission.
abstract: Metal nanostructures with conical shape, vertical alignment, large ratio of cone height and curvature radius at the apex, controlled cone angle, and single-crystal structure are ideal candidates for enhancing field electron-emission efficiency with additional merits, such as good mechanical and thermal stability. However, fabrication of such nanostructures possessing all these features is challenging. Here, we report on the controlled fabrication of large scale, vertically aligned, and mechanically self-supported single-crystal Cu nanocones with controlled cone angle and enhanced field emission. The Cu nanocones were fabricated by ion-track templates in combination with electrochemical deposition. Their cone angle is controlled in the range from 0.3° to 6.2° by asymmetrically selective etching of the ion tracks and the minimum tip curvature diameter reaches down to 6 nm. The field emission measurements show that the turn-on electric field of the Cu nanocone field emitters can be as low as 1.9 V/μm at current density of 10 μA/cm(2) (a record low value for Cu nanostructures, to the best of our knowledge). The maximum field enhancement factor we measured was as large as 6068, indicating that the Cu nanocones are promising candidates for field emission applications.
authors.affiliation: Materials Research Center, Institute of Modern Physics, Chinese Academy of Sciences , Lanzhou 730000, P. R. China.|Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong, China.
authors.forename: Jing Lai
authors.initials: JL
authors.lastname: Duan
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong, China.
authors.forename: Dang Yuan
authors.initials: DY
authors.lastname: Lei
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Chen
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong, China.
authors.forename: Shu Ping
authors.initials: SP
authors.lastname: Lau
authors.affiliation: Department of Engineering, Electrical Engineering Division, University of Cambridge , 9 JJ Thomson Avenue, CB3 0FA, Cambridge, United Kingdom.
authors.forename: William I
authors.initials: WI
authors.lastname: Milne
authors.affiliation: Materials Research Department, GSI Helmholtz Centre for Heavy Ion Research , 64291 Darmstadt, Germany.
authors.forename: M E
authors.initials: ME
authors.lastname: Toimil-Molares
authors.affiliation: Materials Research Department, GSI Helmholtz Centre for Heavy Ion Research , 64291 Darmstadt, Germany.|Materials Science, Technische Universität Darmstadt , 64287 Darmstadt, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Trautmann
authors.affiliation: Materials Research Center, Institute of Modern Physics, Chinese Academy of Sciences , Lanzhou 730000, P. R. China.
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
keywords: copper; field emission; ion track template; nanocone array; single-crystal