Abstract
Diamond surfaces with suitable adsorbed chemical species can exhibit both negative and positive electron affinities, arising from the complex electrostatic interplay between adsorbates and surface carbon atoms of diamond lattice. We present the results of density functional calculations into the energetics and the electron affinity of diamond (100) surfaces terminated with the oxides of selected transition metals. We find that for a correct stoichiometry, oxides of transition metals, such as Ti and Zn, exhibit a large negative electronic affinity of around 3 eV. The desorption of transition metal oxides is found to be highly endothermic. We therefore propose that transition metal oxides are promising for the surface coating of diamond-based electron emitters, as these exhibit higher thermal stability in comparison to the commonly used Cs-O termination, while retaining the advantage of inducing a large negative electron affinity. © (2013) Trans Tech Publications, Switzerland.