The investigation of the field emission (FE) properties of carbon nanotube (CNT) films by a scanning anode FE apparatus, reveals a strong dependence on the density and morphology of the CNT deposit. Large differences between the microscopic and macroscopic current and emission site densities are observed, and explained in terms of a variation of the field enhancement factor β. As a consequence, the emitted current density can be optimized by tuning the density of CNTs. Films with medium densities (on the order of 107 emitters/cm2, according to electrostatic calculations) show the highest emitted current densities.

Scanning anode field emission microscopy is used to map the electron emission current I(x,y) under constant anode voltage and the electron extraction voltage V(x ,y) under constant emission current as a function of tip position on carbon based thin film emitters. The spatially resolved field enhancement factor {3(x,y) is derived from V(x,y) maps. It is shown that large vaiiations in the emission site density (ESD) and current density can be explained in terms of the spatial variation of the field enhancement {3(x,y). Comparison of {3(x,y) and l(x,y) shows that electron emission currents are correlated to the presence of high aspect ratio field enhancing structures. We introduce the concept of field enhancement distribution fl.{3), which is derived from {3(x,y) maps to chm•acterize the field emission properties of thin films. In this context f({3)df3 gives the number of emitters on a unit surface with field enhancement factors in the interval ([3,f3+df3). It is shown experimentally for the carbon thin film emitters investigated that /(/3) has an e~po~en~ial dependence with regard to the field enhancement factor {3. The field enhancement d1stnbutton function fl.{3) can be said to give a complete characterization of the thin film field emission properties. As a consequence, the emitted current density and ESD can be optimized by tuningfl.{3) of the emitting thin film.

We report on the functional capabilities of a scanning anode field emission microscope (SAFEM) which combined with a phosphor screen is used to investigate and con-elate individual electron emission site characteristics of low threshold thin film electron emitters in the micrometer regime. Spatially recorded extraction voltage V(x,y) maps under constant emission cutTent or emission cmrent J(x,y) maps under constant anode voltage reveal spatially divergent emission properties on thin film emitters. The V(x,y) maps are used to derive the field enhancement {3(x,y) maps which give a better description of the thin film emission properties as compared to electJ.ic threshold fields which depends on anode-cathode geometry. Individual emission site cu1rent stability of thin film emitters can be i.llvestigated with the SAFEM, and a high-resolution field emission microscope to investigate the environmental stability of single carbon nanotubes mounted on filamepts as a function of partial gas pressures and temperature.

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Natural diamond (100) surface, highly (100) oriented chemical vapour deposited (CVD) diamond films, and interface layers between the silicon substrate and the CVD diamond are analysed by X-ray induced photoelectron diffraction (XPD). Measured 2 n patterns of natural diamond Cls emission at 964 eV are compared to single scattering cluster (SSC) calculations. Excellent agreement is found and comparisons show that photoelectron forward focusing is much less prominent in carbon solids than in previously studied, heavier elements. No orientation is observed for silicon evaporated on natural diamond and the interface shows no carbide formation. After 8 min of oriented diamond growth in microwave plasma, XPD shows an (100) oriented Sic interface and a preferential orientation of the microscopic crystals. SSC simulations confirm the presence of PSiC at the interface. It appears that the Sic interface is always oriented independent of the parameters used for the bias treatment.