Light emission from an oxygen covered copper surface by ion bombardment

Abstract

Light emission from oxygen covered metal surface is used to investigate the sputtering yield, SO, and the sticking coefficient, cS, of oxygen atoms on the surface of a polycrystalline copper target. The spectral lines of Cu I emitted from sputtered excited atoms under Ar+ and Ne+ ion bombardment of a polycrystalline copper target are measured as a function of the oxygen partial pressure, wavelength and beam energy. The light emission for two Cu I lines (3247 and 3274 Å) are proportional to the oxygen partial pressure (∼1 × 10-4 Torr). Above 2 × 10-4 Torr, the light intensities start to decrease in accordance with observations in other metal measurements. The intensities of Cu I spectral lines are measured as a function of time and oxygen partial pressures, and the sputtering yields and the sticking coefficient are determined from the curves of spectral lines directly. For 10 and 20 keV Ar+ ions bombarded the copper surface, the oxygen sputtering yields from the copper surface are 0.34 and 0.22 respectively. For Ne+ ions with 5 and 10 keV, the oxygen sputtering yields are 0.87 and 0.59 respectively. The sticking coefficient of oxygen atoms on the copper surface is constant in all measurements and is estimated as around (2.34 ± 0.49) × 10-3. Combined results with this experiment and a previous measurement [Surf. Sci. 471 (2000) 219-24], we believe that beam induced light emission is a useful technique to measure the oxygen-sticking coefficient on metal surfaces. © 2001 Elsevier Science B.V. All rights reserved.