Sputtering of molybdenum and tungsten nano rods and nodules irradiated with 150 eV argon ions

Applied Surface Science, Volume 331, 15 March 2015, Pages 299–308.

N.M. Ghoniem1, Alp Sehirlioglu2, Anton L. Neff3, Jean-Paul Allain3, Brian Williams4, Reza Sharghi-Moshtaghin5.

  1.  Mechanical & Aerospace Engineering Department, UCLA, Los Angeles, CA 91344, United States
  2. Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, OH 44106, United States
  3. Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois, 216 Talbot Laboratory, MC-234, Urbana, IL 61801, United States
  4. Ultramet Inc., Pacoima, CA 91331, United States
  5. Department of Materials Science and Engineering, Case Western Reserve University & SCSAM, Cleveland, OH 44106, United States

 

Abstract

The influence of surface nano architecture on the sputtering and erosion of tungsten and molybdenum is discussed. We present an experimental investigation of the effects of low energy (150 eV) Ar ions on surface sputtering in Mo and W nano-rods and nano-nodules at room temperature. Measurements of the sputtering rate from Mo and W surfaces with nano architecture indicate that the surface topology plays an important role in the mechanism of surface erosion and restructuring. Chemical vapor deposition (CVD) is utilized as a material processing route to fabricate nano-architectures on the surfaces of W and Mo substrates. First, Re dendrites form as needles with cross-sections that have hexagonal symmetry, and are subsequently employed as scaffolding for further deposition of W and Mo to create nano rod surface architecture. The sputtering of surface atoms in these samples shows a marked dependence on their surface architecture. The sputtering rate is shown to decrease at normal ion incidence in all nano-architecture surfaces as compared to planar surfaces. Moreover, and unlike an increase in sputtering of planar crystalline surfaces, the current measurements show a decrease in the net sputtering rate at oblique angles as compared to normal incidence. Energy deposition in the near surface layer shows that W is also amorphized at room temperature by low energy Ar ions to a depth of 5–10 nm.

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