Depth of origin of sputtered atoms: Experimental and theoretical study of Cu/Ru(0001)
The depth of origin of sputtered atoms is a subject of considerable interest. The surface sensitivity of analytical techniques such as Secondary Ion Mass Spectrometry (SIMS) and Surface Analysis by Resonance Ionization of Sputtered Atoms (SARISA), and the sputtering properties of strongly segregating alloy systems, are critically dependent on the sputtering depth of origin. A significant discrepancy exists between the predictions of the Sigmund theory and computer sputtering models; in general, the computer models predict a much shallower depth of origin. The existing experimental evidence suggests that most of the sputtered atoms originate in the topmost atomic layer, but until recently, the results have not been definitive. We have experimentally determined the depth of origin of atoms sputtered from surfaces consisting of Cu films of less than two monolayers on a Ru(0001) substrate. The Cu/Ru target was statically sputtered using 3.6 keV Ar/sup +/. The sputtered neutrals were non-resonantly laser ionized and detected using SARISA. The Cu/Ru sputtering yield ratio and the suppression of the Ru sputtering yield were determined for various Cu coverages. The results indicate that the majority of the sputtered atoms originate in the topmost atomic layer. The Cu/Ru system is also modeled using a modified Transport of Ions in Matter (TRIM) code. It was found that TRIM C does not correctly treat the first atomic layer, resulting in a serious underestimate of the number of sputtered atoms which originate in this layer. The corrected version adequately describes the results, predicting that for the experimental conditions roughly two-thirds of the sputtered atoms originate in the first atomic layer. These results are significantly greater than the Sigmund theory estimate of >40%. 26 refs., 3 figs., 1 tab.
- Research Organization:
- Argonne National Lab., IL (USA); Pittsburgh Univ., PA (USA). Surface Science Center; Hahn-Meitner-Institut fuer Kernforschung Berlin G.m.b.H. (Germany, F.R.)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 5833232
- Report Number(s):
- CONF-871125-14; ON: DE88002848
- Resource Relation:
- Conference: 34. national vacuum symposium and topical conference, Anaheim, CA, USA, 2 Nov 1987; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
SPUTTERING
COMPUTERIZED SIMULATION
THIN FILMS
COPPER
EXPERIMENTAL DATA
RUTHENIUM
THEORETICAL DATA
DATA
ELEMENTS
FILMS
INFORMATION
METALS
NUMERICAL DATA
PLATINUM METALS
SIMULATION
TRANSITION ELEMENTS
656003* - Condensed Matter Physics- Interactions between Beams & Condensed Matter- (1987-)