Depth of Origin of Sputtered Atoms

Abstract

The depth of origin of sputtered atoms is currently a very important quantity in surface physics. The importance is best observed by examining the literature on computer simulations and theoretical calculations. Despite this interest, it is very hard to find experimental measurements of the depth of origin of sputtered atoms, which is probably due to the difficulty of such experiments. A good determination of the depth of origin should be done on a well characterized system and without damaging it. The results reported here are obtained from 1–2 monolayers of Cu on a Ru(0001) single crystal surface. The first 2 monolayers of Cu evaporated onto Ru(0001) is known to exhibit a layer by layer growth[l]. The sputtering is studied in the Surface Analysis by Resonance Ionization of Sputtered Atoms(SARISA) apparatus[2], where it is possible to do the determination before the overlayer is damaged by the ion beam. One monolayer of Cu on Ru is found to give a ratio of 3.2 between Cu and Ru in the sputtered flux for 4 keV normal incidence Ar ions.

Work supported by the U.S. Department of energy, BES-Material Science, under contract W-31–109-Eng-38.