Journal of Physics: Condensed Matter

Texto completo: acesso restrito. p. 1-9 Submitted by Suelen Reis (suziy.ellen@gmail.com) on 2014-05-15T14:17:45Z No. of bitstreams: 1 0953-8984_25_28_285106.pdf: 1243512 bytes, checksum: 6df6c734ce1536978c6b4f16757c2e81 (MD5) Approved for entry into archive by Alda Lima da Silva (sivalda@ufba.br) on 2014-09-08T21:03:19Z (GMT) No. of bitstreams: 1 0953-8984_25_28_285106.pdf: 1243512 bytes, checksum: 6df6c734ce1536978c6b4f16757c2e81 (MD5) Made available in DSpace on 2014-09-08T21:03:19Z (GMT). No. of bitstreams: 1 0953-8984_25_28_285106.pdf: 1243512 bytes, checksum: 6df6c734ce1536978c6b4f16757c2e81 (MD5) Previous issue date: 2013 In this work, we present systematic theoretical evidence of a relationship between the point local roughness exponent (PLRE) (which quantifies the heterogeneity of an irregular surface) and the cold field emission properties (indicated by the local current density and the macroscopic current density) of real polyaniline (PANI) surfaces, considered nowadays as very good candidates in the design of field emission devices. The latter are obtained from atomic force microscopy data. The electric field and potential are calculated in a region bounded by the rough PANI surface and a distant plane, both boundaries held at distinct potential values. We numerically solve Laplace's equation subject to appropriate Dirichlet's condition. Our results show that local roughness reveals the presence of specific sharp emitting spots with a smooth geometry, which are the main ones responsible (but not the only) for the emission efficiency of such surfaces for larger deposition times. Moreover, we have found, with a proper choice of a scale interval encompassing the experimentally measurable average grain length, a highly structured dependence of local current density on PLRE, considering different ticks of PANI surfaces.