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The emission of secondary electrons from any material is governed by electron excitation in the bulk, their transport to the surface, and their escape through the surface into the vacuum. Here, we address the question of the transport of electrons in polycrystalline diamond and amorphous carbon membranes and discuss the factors that limit it. The results of the measurements of the escape depth of the secondary electrons from the membranes of submicron polycrystalline diamond and amorphous carbon films induced by the hydrogen ion impact are reported here. It is found that the escape depth for the secondary electrons emitted from diamond scales with the grain size of the crystallites in the polycrystalline diamond films and it can be very large. In contrast, for the case of the amorphous carbon membranes, we find this depth to be much shorter. The extremely high electron emission yield, which have been measured following the slowing down of the electrons or ions in diamond, can be explained by the fact that secondary electrons can move rather freely in diamond, hence, can reach the surface from large distances inside the diamond sample. [ABSTRACT FROM AUTHOR]

Abstract: A simple method for extremely low fluence ion implantation is described. It is based on implanting ions which are Rutherford backscattered (RBS) from a thin gold layer into the desired target. This method enables ion implantations to be carried out, as are needed to realize quantum centers on the atomic scale to serve as qubits and other nano sized devices. The required implantation fluences are orders of magnitude below the commonly-used current integration capabilities; hence control on the implanted fluence is usually complicated. The described method enables control on the implanted fluence even when extremely low. The dependence of the energy and fluence of scattered ions on the angle and scattering target thickness is analyzed by using SRIM simulations. These are verified for the case of N scattering implantation by direct counting in a surface barrier detector and for the case of Xe by counting the tracks that scattered and implanted Xe ions leaved in HOPG as viewed by scanning probe microscopy. [Copyright &y& Elsevier]

The potential use of CVD diamond films as a cold cathode material is limited by several factors associated with fast and slow material degradation processes induced by interaction that gives rise to secondary electron (SE) emission. In particular, the negative electron affinity (NEA) loss which has been attributed to Hydrogen detachment from the film surface, happens during ion or electron bombardment and seriously affects SE emission. Using the published results of NEA temperature dependence and connecting them with SE low-energy spectra at different temperatures, we obtained a linear approximation between NEA and surface Hydrogen coverage. The fast ion dose-dependent changes in SE yield are explained by high production rate of radiation defects near their projected range, and the experimentally obtained cross-section of that process is assessed. As a way to improve SE emission durability, we show here the possibility of surface hydrogenation performed at relatively low temperature of 350 °C to cause complete hydrogen termination of CVD diamond film surface. Subsequent low dose proton bombardment causes significant decrease in ion induced electron emission (IIEE) coefficient γ. Repeated ‘cold’ and ‘hot’ re-hydrogenation only partially recovers the electron emission properties of the film, implying the existence of residual Boron-defect complexes. [Copyright &y& Elsevier]

The nitrogen vacancy color center (NV-) in diamond is of great interest for photonic applications. Diamond nano-photonic structures are often implemented using focused-ion-beam (FIB) processing, leaving a damaged surface which has a detrimental effect on the color center luminescence. The FIB processing effect on single crystal diamond surfaces and their photonic properties is studied by time of flight secondary ion mass spectrometry and photoluminescence. Exposing the processed surface to hydrogen plasma, followed by chemical etching, drastically decreases implanted Ga concentration, resulting in a recovery of the NV- photo-emission and in a significant increase of the NV-/NV0 ratio. [ABSTRACT FROM AUTHOR]

The electron emission yields (γ) from conductive (B doped) and undoped chemical vapor deposited diamond caused by light (protons) and heavy (argon) ion impact were measured as functions of ion dose and energy (40–300 keV). Very large values of γ are obtained for the case of B doped diamond for both ions. Whereas the emission due to Ar is found to decay very rapidly towards the low γ value measured for graphite, it remains persistently very high (γ∼25) for the case of protons, indicating possible application of diamond as a sensitive detector for light ions. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Extraordinarily high ion-beam induced electron yields are seen from polycrystalline diamond surfaces for high energy H+, He+ and Ar+ ions. This is attributed to the negative electron affinity of the diamond surface. However, the yield decays rapidly with dose, limiting the potential applications. The mechanism for decay is suggested to be electron-stimulated desorption of surface hydrogen, which removes the negative electron affinity responsible for high yields. [Copyright &y& Elsevier]