V. S. Chernysh

Measurements of angular distributions of sputtered material as a new tool for surface-segregation studies: Segregation in CuPt alloys

Abstract The angular distribution of copper and platinum sputtered by argon ions from polycrystalline CuPt targets at 77 K has been measured by a collection technique. The argon-ion energy has been varied from 1.25 to 320 keV. For bombardment energies above 20 keV, differences in the angular distributions for the two elements indicate a strong copper segregation to the surface during bombardment.

Effects of substrate treatment on the initial growth mode of indium-tin-oxide films

The initial growth mode of indium tin oxide (ITO) on polycarbonate (PC) substrates was investigated. Some of the PC substrates were bombarded by 1-keV Ar ions in an oxygen environment to modify the substrate surface before ITO sputter deposition. The initial part of the film growth was transformed from a three-dimensional island growth to a two-dimensional like growth as a result of the surface treatment. The change of the growth mode was attributed to oxygen-bound functional groups newly formed on the PC surface. Models based on thermodynamic theory and on atomic kinetic approach are presented to explain the transition, respectively.

The angular distribution of material sputtered from AgAu and CuPt by 20–80 keV argon

Abstract The material sputtered by 20–80 keV argon from films of AgAu and CuPt has been collected on a semicircular aluminum collector. The elemental composition of the sputtered material was determined through the Rutherford scattering of 2 MeV α particles. To ensure a sufficient amount of collected material, irradiation doses were substantially larger than those at which the total sputtered flux had attained a stoichiometric composition. In spite of the fact that the AgAu targets showed a strong crystalline texture while the CuPt targets consisted of fine-grained random polycrystalline materials, the two targets displayed close similarities in the angular distribution of the ratio between light and heavy elements. Material sputtered further than 70° away from the normal could not be measured, but within the investigated region, the composition of the collected material never deviated by more than 15% from the average composition of the sputtered flux.

Angular distributions of Ni and Ti atoms sputtered from a NiTi alloy under He+ and Ar+ ion bombardment

Abstract The angular distributions of sputtered components were measured for NiTi polycrystalline alloy under 9 keV Ar + and He + ions bombardments with various fluences in ultrahigh vacuum. Combination of Rutherford Backscattering Spectrometry (RBS) and Auger Electron Spectrometry (AES) techniques allowed us to observe enhanced concentration of Ni over a layer with thickness comparable to a primary He + ions penetration depth due to selective sputtering of Ti atoms and radiation-induced diffusion processes. A preferential emission of Ni atoms towards the surface normal was observed during bombardment by both He + and Ar + ions. More forward-peaked “over-cosine” angular distributions of sputtered Ni in comparison with those for Ti atoms have been measured. Nonstoichiometric sputtering of NiTi alloy dependent on emission angle was observed for bombardment fluence of He + well below that needed for the steady-state altered layer formation. To explain the peculiarities of NiTi sputtering, an interpretation is discussed in terms of sputtering due to backscattered He + ions.

Neutron generation in dense femtosecond laser plasma of a structured solid target

We report neutron production by the 2H(d, n)3He reaction induced upon the illumination of a solid nanostructured target by femtosecond laser pulses of intensity 20 PW/cm2 (1 PW = 1015 W). The target was structured through the preliminary illumination by a laser pulse of the same intensity.

Angular distribution of atoms sputtered from germanium by 1–20 keV Ar ions

The angular distribution of atoms sputtered from germanium under 1–20 keV Ar+ ion bombardment (normal incidence) has been studied experimentally and using computer simulations. A collector technique combined with Rutherford backscattering to analyze the distribution of collected material was used. In addition, the surface topography was under control. It was found that the experimental angular distribution of sputtered atoms (E 0=3–10 keV) could be approximated by the function cos n θ with n≈ 1.65. Such a high value of n is connected with the surface scattering of ejected atoms and a noticeable contribution of backscattered ions to the formation of the sputter flux (the mass effect). The target surface was found to be practically flat even at ion fluencies ∼1018 ions/cm2. The results obtained are compared with data from the literature, including our recent data on Si sputtering.

Fabrication of ultrafine silicon layers on sapphire

The effect of energy, dosage, and temperature of irradiation of silicon-on-sapphire structures by Si+ ions, as well as parameters of recrystallization annealing, on crystallinity of silicon film is shown. Implantation conditions and recrystallization annealing conditions are determined.

Selective sputtering of single crystals of binary semiconductor compounds

Abstract The method of electron Auger-spectrometry is used to study the composition of the sputtered A(111) and B(―1―1―1) faces of InSb dendrites and the deposits sputtered from them. The obtained noticeable anisotropy of the In and Sb distribution within ejection angles ± 50° to directions has been found to be in good qualitative agreement with the results of computer calculations. It has been shown that the observed compositions of the dendrites and films vary depending on sputtering time.

Angular distributions of particles sputtered from polycrystalline platinum

Abstract The angular distributions of sputtered particles for 3–10 keV argon-ion bombardment of polycrystalline platinum at normal incidence have been investigated both experimentally and by computer simulation using the program TRIM.SP. Two types of targets were used. One is a fine-grained Pt polycrystal, the other is rolled sheet Pt. The angular distributions were measured applying RBS of the material deposited on a collector. For fine-grained platinum the angular distributions are cupola shaped and slightly overcosine. For rolled platinum the distributions are much more overcosine with a strong central Wehner spot due to the texture caused by rolling. Results from computer simulation show that the effect of the surface binding energy on the shape of the angular distribution is negligible. The dependence of the shape of the angular distribution on the ion energy interval from 3.5 to 10 keV was also found to be very weak. Good agreement has been found between the experimental and computed results for fine-grained platinum.

Medium energy ion scattering spectroscopy: Study of germanium amorphization under ion irradiation

An experimental setup for medium energy ion scattering spectroscopy allowing materials elemental composition diagnostics has been developed. A target composed of single-crystalline Ge with a smooth surface and structural inhomogeneity several nanometers thick has been prepared for conducting the experiments. Experiments have shown that the depth resolution of the method was 6 Å.