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 photoelec tron emission induced by KrCl excimer laser (222 nm wavelength) pulses of a nanosecond duration, were studied. The Ni/diamond structures wer e prepared by deposition of ultrathin nickel coatings (approximate to 2 nm thick) onto 1 mu m thick diamond films on Si. The photocurrent in duced by the UV laser pulses from a Ni-coated diamond surface was foun d to increase as compared with the photocurrent from the original film surface. Using Auger electron spectroscopy (AES) and X-ray photoelect ron spectroscopy (XPS) techniques, the electronic structure of the Ni- coated and as-grown surfaces, and the chemical state of nickel and sur face band bending, were investigated. It is discussed that the formati on of the downwards band bending and a lowering of the surface work fu nction are responsible for the observed enhancement of laser-induced e lectron emission from the Ni-coated diamond films. (C) 1998 Elsevier S cience S.A. All rights reserved.