Is There a Crystal Orientation where the Sputter Yield Corresponds to Amorphous Material?
Fast analysis tools allow the investigation of the sputtering behaviour of tens of thousands of individual crystal grains.
Sputter yields versus crystal orientations as an inverse pole figure. The sputtering experiment was performed on a polished polycrystalline tungsten sample using a 30 keV Ga ion beam.
In calculations it is often assumed that there are broad regions of crystal orientations in which the sputter yield under ion bombardment is essentially the same as in an amorphous material. However it is for instance well known, that the yield is especially low in some special crystal orientations.
Nowadays, systematic studies of the yield as a function of the crystal orientation are possible, because of the recent improvements in the electron backscatter diffraction technique (EBSD). Crystal orientation measurements are several orders of magnitude faster than in former times.
Extended EBSD orientation maps of polycrystalline samples can therefore be measured in reasonable time. The corresponding sputter yield on each individual single crystal grain can be measured by confocal laser scanning microscopy.
By comparing such experiments with independent molecular dynamics simulations we found that the sputter rate for 30 keV Ga ions on metals changes continuously with the crystal orientation - there is no extended region of crystal orientations that would behave like amorphous material.
This work has recently been published in “Physical Review Letters”:
https://doi.org/10.1103/PhysRevLett.125.225502