Bu, CaixiaColumbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA
Author
Morrissey, Liam S.NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA - Faculty of Engineering and Applied Science, Memorial University, NL, Canada A1B 3X7
Author
Bostick, Benjamin C.Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA
Author
Burger, Matthew H.Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218, USA
We have measured the absolute doubly differential angular sputtering yield for 20 keV Kr+ impacting a polycrystalline Cu slab at an incidence angle of θi = 45° relative to the surface normal. Sputtered Cu atoms were captured using collectors mounted on a half dome above the sample, and the sputtering distribution was measured as a function of the sputtering polar, θs, and azimuthal, fs, angles. Absolute results of the sputtering yield were determined from the mass gain of each collector, the ion dose, and the solid angle subtended, after irradiation to a total fluence of ∼1 × 1018 ions/cm2. Our approach overcomes shortcomings of commonly used methods that only provide relative yields as a function of θs in the incidence plane (defined by the ion velocity and the surface normal). Our experimental results display an azimuthal variation that increases with increasing θs and is clearly discrepant with simulations using binary collision theory. We attribute the observed azimuthal anisotropy to ion-induced formation of micro- and nano-scale surface features that suppress the sputtering yield through shadowing and redeposition effects, neither of which are accounted for in the simulations. Our experimental results demonstrate the importance of doubly differential angular sputtering studies to probe ion sputtering processes at a fundamental level and to explore the effect of ion-beamgenerated surface roughness.
Bu, C., Morrissey, L. S., Bostick, B. C., Burger, M. H., Bowen, K. P., Chillrud, S. N., Domingue, D. L., Dukes, C. A., Ebel, D. S., Harlow, G. E., Hillenbrand, P.-M., Ivanov, D. A., Killen, R. M., Ross, J. M., Schury, D., Tucker, O. J., Urbain, X., Zhang, R., & Savin, D. W. (2024). Absolute doubly differential angular sputtering yields for 20 keV Kr+ on polycrystalline Cu. Journal of Applied Physics, 135(3), 135-035302. https://doi.org/10.1063/5.0184417 (Original work published 2024)