Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5368686 | Applied Surface Science | 2006 | 7 Pages |
The oxygen induced faceting of the macroscopic W[1Â 1Â 1] tip has been studied for oxygen exposures in the range 0.5-31Â L and annealing temperatures 800-1800Â K using the field ion microscopy (FIM) technique. After annealing at temperatures lower than 800Â K, higher than 1850Â K or for exposures lower than 0.5Â L faceting was not observed. For exposures 0.5-1.9Â L and annealing temperatures 800-1600Â K well developed {1Â 1Â 2} facets with sharp edges formed. For exposures higher than 2.0Â L edges of the {1Â 1Â 2} facets were broadening and disappearing, what has been attributed to the formation of three-dimensional tungsten oxides. The oxides could be easily removed by annealing the tip at 1700Â K, what leads to formation of sharp facet edges. On the basis of these results a modified procedure of the ultrasharp tip fabrication has been proposed.