Tuning the electron affinity of CVD diamond with adsorbed caesium and oxygen layers

Abstract

Abstract The adsorption of Cs on CVD diamond is observed to produce the condition of negative electron affinity (NEA). The intensity of the NEA photoelectron peak together with the thermal and chemical stability of the NEA condition are measured and are found to be sensitive to the chemical species terminating the diamond surface prior to caesiation. Diamond surfaces that have been etched with acid and annealed to 1400 K, or simply oxidised at 300 K before caesiation display strong NEA characteristics that are chemically stable in air and thermally stable to 650 K. Diamond surfaces that have been hydrogenated prior to caesiation show a comparatively weaker NEA condition that is thermally and chemically unstable. The results are rationalised on the basis of band bending and reactive interface formation.