Field emission from as-grown and surface modified BN and CN thin films

Abstract

We have investigated the electron field emission characteristics of BN and CN on highly conductive silicon thin films deposited by End-Hall ion source and electron cyclotron resonance plasma source-assisted physical vapor deposition. The thermal processing and surface laser modification effects on the field emission properties were investigated. Current density-field emission characteristics Iη(E) were tested in a high vacuum environment. Mg-doped BN thin films on silicon exhibited a turn-on field as low as 25 V/μm and a current density higher than 1 A/cm2. The deposition of a thin BN layer on copper lithium (CuLi) metallic substrate yields surfaces with a 75 V/μm onset field and a current density 1000 times higher than that obtained from uncoated surfaces. Under high vacuum laser annealing BN coated CuLi showed no enhancement but more stable emission characteristics. Our results show also that pulsed ultraviolet laser irradiation of CN films in vacuum results in an increase of the field emission current densities and a reduction in threshold field values. The turn-on fields of the irradiated surfaces depend strongly upon the energy density of the laser beam. In addition, the electroconductivity properties of BN and CN surface mapping have been performed using scanning tunneling field emission microscopy. The surface topography mapping and its correlation to the field emission properties were investigated. Preliminary results on surface mapping suggest that the surface relief plays some role in field emission enhancement.