Sputtering of molecules from ZnS, CdS, and FeS2
Abstract
An open question remains as to whether molecules form as a result of simultaneous ejection of neighboring atoms from a solid or because of a molecular band that exists in the solid metal target before sputtering. This was addressed by sputtering experiments using a binary target, where the constituents of the sputtered molecules may not occupy nearest neighbor sites in the crystal. A study was conducted on single crystals of three metal-sulfides with two different lattice structures, using laser post-ionization mass spectrometry to detect neutral sputtered species. The single crystals used for these experiments were synthetically grown CdS and ZnS with the Wurtzite structure, and natural FeS2 with the cubic structure. The FeS2 samples were ultrasonically cleaned with trichloroethane, acetone, and methanol before insertion in the UHV chamber. The latter two solvents were used to clean CdS and ZnS. In sputtering metal sulfides of different structures, sputtered molecules with constituents that do not have a bond in the solid were observed. In the case of the metal dimers, the sputtered atom exceeds in number the metal dimer, whereas S is predominantly sputtered as S2 from all three samples. The results presented in this paper also suggest that some form of recombination mechanism (inside or outside the solid) is responsible for formation of molecules. Our data also show that the sputtered molecules form a significant percentage of the sputtered species. Therefore, it is important for quantitative analyses to obtain an accurate measure of molecular sputtering yields.
- Publication:
-
Presented at the Fall Meeting of the Materials Research Society
- Pub Date:
- November 1990
- Bibcode:
- 1990mrs..meetR....N
- Keywords:
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- Crystal Structure;
- Inorganic Sulfides;
- Recombination Reactions;
- Single Crystals;
- Sputtering;
- Ultrahigh Vacuum;
- Vacuum Chambers;
- Dimers;
- Mass Spectroscopy;
- Zinc Sulfides;
- Solid-State Physics