UV laser-induced electron emission from diamond films coated with ultrathin nickel layers

The effects of the surface modification of diamond films with thin Ni layers and of the influence of the Ni/diamond structures, on photoelectron emission induced by KrCl excimer laser (222 nm wavelength) pulses of a nanosecond duration, were studied. The Ni/diamond structures were prepared by deposition of ultrathin nickel coatings (approximate to 2 nm thick) onto 1 mu m thick diamond films on Si. The photocurrent induced by the UV laser pulses from a Ni-coated diamond surface was found to increase as compared with the photocurrent from the original film surface. Using Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) techniques, the electronic structure of the Ni-coated and as-grown surfaces, and the chemical state of nickel and surface band bending, were investigated. It is discussed that the formation of the downwards band bending and a lowering of the surface work function are responsible for the observed enhancement of laser-induced electron emission from the Ni-coated diamond films. (C) 1998 Elsevier Science S.A. All rights reserved.