A tension increment after sputter deposition of 1 nm of WSi2 onto sputtered Si was observed at low Ar gas pressures. Wafer curvature data on multilayers were found to have a periodic variation corresponding to the multilayer period, and this permitted statistical analyses to improve the sensitivity to small stresses. The observation of tension instead of compression in the initial stage of growth is new and a model invoking surface rearrangement is invoked. The data also bear on an unusual surface smoothing phenomena for sputtered Si surfaces caused by the sputter deposition of WSi2 . We furthermore report that for low Ar pressures the Si layers are the predominant source of built-up stress.
We have developed a wedge-loaded double-cantilever beam adhesion measurement set-up for thin films deposited on glass by sputtering. The test is described in details. Results on the Glass/sublayer/Ag/ZnO multilayer provide evidence that \SnOd or \TiOd perform better than ZnO as a sublayer. Then however, rupture within the multilayer shifts to the upper Ag/ZnO interface. The latter is shown to be tougher than the lower ZnO/Ag interface, an asymmetry due to non-equilibrium interfacial structures.
Hyperbolic metamaterials create artificial optical anisotropy using metallic wires suspended in a dielectric medium, or alternating layers of a metal and dielectric. Here we fabricated ZnO/Al:ZnO (AZO) multilayers by the RF magnetron sputtering deposition technique. Our fabricated multilayers satisfy the conditions required for a type I hyperbolic metamaterial. The optical response of individual AZO and ZnO films, as well as the multilayered film were investigated via angular transmittance and spectroscopic ellipsometry measurements. The optical response of the multilayered system is predicted…
Copper ferrite thin films were rf sputtered at a power of 50W. The as deposited films were annealed in air at 800°C and slow cooled. The transmission electron microscope (TEM) studies were carried out on as deposited as well as on slow cooled film. Significantly larger defect concentration, including stacking faults, was observed in 50W as deposited films than the films deposited at a higher rf power of 200W. The film annealed at 800°C and then slow cooled showed an unusual grain growth upto 180nm for a film thickness of ~240nm. These grains showed Kikuchi pattern.
NbN films were deposited on SS substrates by reactive DC magnetron sputtering at various N2 flow rates and substrate biasing. Effect of N2 flow rate and substrate biasing has been studied on deposition rate, surface hardness, crystal-structure and adhesion values. Process parameters were optimized for deposition of NbN coatings. NbN coatings were then deposited on to MS substrates as such and with Nb interlayer deposited by magnetron sputtering. The thickness of interlayer was 2 \mum. The duplex coating has been studied for the improvement with respect to surface hardness by Knoop micro indent…
We investigated structural, magnetic and electrical properties of sputter deposited Mn-Fe-Ga compounds. The crystallinity of the Mn-Fe-Ga thin films was confirmed using x-ray diffraction. X-ray reflection and atomic force microscopy measurements were utilized to investigate the surface properties, roughness, thickness and density of the deposited Mn-Fe-Ga. Depending on the stoichiometry, as well as the used substrates (SrTiO3 (001) and MgO (001)) or buffer layer (TiN) the Mn-Fe-Ga crystallizes in the cubic or the tetragonally distorted phase. Anomalous Hall effect and alternating gradient magn…
Multilayers of hydrogenated ultrathin (3 nm) amorphous a-Si and a-Ge layers prepared by sputtering have been studied by atomic force microscopy (AFM) and transmission electron microscopy (TEM) to check the influence of annealing on their structural stability. The annealed multilayers exhibit surface and bulk degradation with formation of bumps and craters whose density and size increase with increasing hydrogen content and/or annealing temperature and time. Bumps are due to the formation of H2 bubbles in the multilayer. The craters are bumps blown up very likely because of too high a gas press…
We grow epitaxial Sm-Co thin films by sputter deposition from an alloy target with a nominal SmCo5 composition on Cr(100)-buffered MgO(100) single-crystal substrates. By varying the Ar gas pressure, we can change the composition of the film from a SmCo5-like to a Sm2Co7-like phase. The composition, crystal structure, morphology and magnetic properties of these films have been determined using Rutherford Backscattering, X-ray diffraction and magnetization measurements. We find that the various properties are sensitive to the sputter background pressure in different ways. In particular, the latt…
Cross contaminations are observed on sample surfaces by AES and XPS, if multiple samples are mounted on one sample holder and a neighbouring sample was sputter depth profiled. During sputter depth profiling sputtered material is deposited on inner surfaces of the instrument. In a secondary sputter process, which is due to species leaving the primary sputter target with higher kinetic energy, the previously deposited material is transported from the inner surfaces to the other samples mounted on the sample holder. This Reflective Sputtering is utilized to deposit ultra-thin layers on sample sur…
Ta (100 nm) / NdFeB (5 $μ$m) / Ta (100 nm) films have been deposited onto Si substrates using triode sputtering (deposition rate ~ 18 $μ$m/h). A 2-step procedure was used : deposition at temperatures up to 400 C followed by ex-situ annealing at higher temperatures. Post-deposition annealing temperatures above 650 C are needed to develop high values of coercivity. The duration of the annealing time is more critical in anisotropic samples deposited onto heated substrates than in isotropic samples deposited at lower temperatures. For a given set of annealing conditions (750 C/ 10'), high heating …
We studied the in-plane magnetic anisotropy of rf (radio frequency) sputtered [(FeTaN)/(TaN)](n) multilayers synthesized on Si substrates. In the multilayers where n=5, the FeTaN thickness is fixed at 30 nm and the thickness of TaN, t(TaN), is varied from 0 to 6.0 nm, we observed a clear trend that, with increasing t(TaN), the values of coercivity, grain size, and amplitude of maximum magnetoresistance (MR) of the samples all decrease first and then increase after reaching a minimum when t(TaN) is around 2.0-4.0 nm. This trend is also associated with an evolution of in-plane magnetic anisotrop…
To engineer strain relaxation of sputtered BST thin films on Pt-Si wafers, homo-buffer layer method was applied to eliminate Pt hillock formation. Thin BST homo-buffer layers were deposited at room temperature and subsequently the main BST layer was deposited at 650°C, Pt hillock free BST films were obtained with homo-buffer thickness above 5 nm. Relatively good electrical properties were obtained for BST thin films with 15 and 25 nm homo-buffer layer (T= 30 % at 5V and tan δ= 0.018).
In this paper we report the deposition of epitaxial thin films of Nd1-xSrxCoO3 with x=0, 0.2 and 0.5 on single crystalline substrates (SrTiO3 and LaAlO3) carried out by means of rf-magnetron sputtering. The deposited films are all completely oriented and epitaxial and characterized by a nanocrystalline morphology. As-deposited films have an average roughness around 1 nm while after the thermal treatment this increases up to 20 nm while preserving the nanocrystalline morphology. All the films deposited on SrTiO3 have shown to be under a certain degree of tensile strain while those on the LaAlO3…
The temperature dependence of the electrical resistivity and magnetoresistance of Xe-ion beam sputtered Fe-Cr multilayers has been investigated. The electrical resistivity between 5 and 300 K in the fully ferromagnetic state, obtained by applying a field beyond the saturation field (H_sat) necessary for the antiferromagnetic(AF)-ferromagnetic(FM) field-induced transition, shows evidence of spin-disorder resistivity as in crystalline Fe and an s-d scattering contribution (as in 3d metals and alloys). The sublattice magnetization m(T) in these multilayers has been calculated in terms of the plan…
We present deposition and characterization of multilayers consisting of 20 repetitions of 15 $Å$ thick permalloy Ni$_{80}$Fe$_{20}$ at. \% (Py) and 5 $Å$ Pt. The samples were prepared by two different sputter deposition methods, namely dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS), that represent low and moderate ionized flux fraction of the film forming material, respectively, for deposition of the Py layers. The effect of substrate roughness, working gas pressure and sputter power on the in-plane uniaxial magnetic anisotropy of the films are studied. The…
Microscopy and diffraction measurements are presented of ultrathin binary alloy films of ruthenium and molybdenum that are obtained by standard sputter deposition. For compositions close to Ru50Mo50, we find the films to be amorphous. The amorphicity of the films is accompanied by a significant reduction of the roughness with respect to the roughness of equally thick films of either ruthenium or molybdenum. We ascribe this to the absence of the grain structure that is characteristic of the polycrystalline films of the separate elements.
Co-sputtered Au-Ni thin films having thickness of 30 nm were deposited on Si(100) substrates and irradiated with 160 keV ^{40}Ar^{+} under ambient condition at a number of fluences and analyzed using Rutherford backscattering spectrometry (RBS). The variation of Au signal counts in the RBS spectra with ion dose has been investigated. The distribution of Au, Ni and Si atoms over various depths within the as deposited and irradiated samples have been computed using the backscattering data by means of a direct analytical method. Au and Si profiles have been fitted with error function and the rela…
High-Sc Al1-xScxN thin films are of tremendous interest because of their attractive piezoelectric and ferroelectric properties, but overall film quality and reproducibility are widely reported to suffer as x increases. In this study, we correlate the structure and electrical properties of Al0.6Sc0.4N with in-situ observations of glow discharge optical emission during growth. This in-situ technique uses changes in the Ar(I) and N2(I) emission lines of the glow discharge during growth to identify films that subsequently exhibit unacceptable structural and electrical performance. We show that a s…
In this work we studied Cu/Co multilayers prepared using dc-magnetron sputtering technique with Ag surfactant. It was found that Ag balances the difference in the surface free energy of Cu and Co and this results in removing the asymmetry in the interface roughness of Cu-on-Co and Co-on-Cu interfaces. As the interfaces become symmetric, we observe a significant enhancement in antiferromagnetic coupling and magneto resistance. Further, a correlation of spin-dependent scattering with the interface roughness is brought by comparing Cu/Co multilayer prepared using different deposition methods. It …
Spin-orbit torque (SOT) magnetization switching of ferromagnets with large perpendicular magnetic anisotropy has a great potential for the next-generation non-volatile magnetoresistive random-access memory (MRAM). It requires a high-performance pure spin current source with a large spin Hall angle and high electrical conductivity, which can be fabricated by a mass production technique. In this work, we demonstrate ultrahigh efficient and robust SOT magnetization switching in all-sputtered BiSb topological insulator - perpendicularly magnetized Co/Pt multilayers. Despite fabricated by the indus…
From Deposition Stress to Surface Reactivity: Strain-Dependent Hydrogen Evolution on Sputtered Platinum Thin Films
Ruhr-University Bochum（波鸿鲁尔大学）；University Duisburg-Essen（杜伊斯堡-埃森大学）；Center for Interface-Dominated High Performance Materials, (ZGH) Ruhr-University Bochum（波鸿鲁尔大学界面主导高性能材料中心）；University of Copenhagen（哥本哈根大学）
50nm thick nanogranular polycrystalline dysprosium thin films have been prepared via ultra-high vacuum DC sputtering on SiO2 and Si wafers. The maximum in-plane spontaneous magnetization at T = 4K was found to be MS4K = 3.28T for samples deposited on wafers heated to 350C with a Neel point of TN = 173K and a ferromagnetic transition at TC = 80K, measured via zero field cooled field cooled magnetization measurements, close to single crystal values. The slightly reduced magnetization is explained in the light of a metastable face centered cubic crystal phase which occurred at the seed interface …
We present topographic and spectroscopic scanning tunneling microscopy measurements taken on a 21 nm thick TiN film at a temperature of 4.2 K -- above the superconducting transition temperature (T_c = 3.8 K) of the sample. The film was polycrystalline with crystallite diameters of d~19 nm, consistent with other films prepared under similar conditions. The spectroscopic maps show on average a shallow V-shape around V_b = 0 V consistent with a sample near the Mott insulation transition. In selected regions on several samples we additionally observed signs of Coulomb blockade. The corresponding p…
Superconducting Nb3Sn films can be synthesized by controlling the atomic concentration of Sn. Multilayer sequential sputtering of Nb and Sn thin films followed by high temperature annealing is considered as a method to fabricate Nb3Sn films, where the Sn composition of the deposited films can be controlled by the thickness of alternating Nb and Sn layers. We report on the structural, morphological and superconducting properties of Nb3Sn films fabricated by multilayer sequential sputtering of Nb and Sn films on sapphire substrates followed by annealing at 950 °C for 3 h. We have investigated th…
We have investigated morphology of the lateral surfaces of PbTe crystal samples grown from melt by the Bridgman method sputtered by Ar+ plasma with ion energy of 50-550 eV for 5-50 minutes under Secondary Neutral Mass Spectrometry (SNMS) conditions. The sputtered PbTe crystal surface was found to be simultaneously both the source of sputtered material and the efficient substrate for re-deposition of the sputtered material during the depth profiling. During sputtering PbTe crystal surface is forming the dimple relief. To be redeposited the sputtered Pb and Te form arrays of the microscopic surf…
5$μ$m thick NdFeB films have been sputtered onto 100 mm Si substrates using high rate sputtering (18 $μ$m/h). Films were deposited at ≤ 500 C and then annealed at 750 C for 10 minutes. While films deposited at temperatures up to 450 C have equiaxed grains, the size of which decreases with increasing deposition temperature, the films deposited at 500 C have columnar grains. The out-of-plane remanent magnetization increases with deposition temperature, reaching a maximum value of 1.4 T, while the coercivity remains constant at about 1.6 T. The maximum energy product achieved (400 kJ/m3) is…
We show that sputtered, pure epitaxial iron films can have high-frequency loss as low as, or lower than, any known metallic ferromagnetic heterostructure. Minimum 34 Ghz ferromagnetic resonance (FMR) linewidths of 41 Oe are demonstrated, some ~ 5-10 % lower than the previous minimum reported for molecular beam epitaxially (MBE) deposited Fe. Intrinsic and extrinsic damping have been separated over 0-40 Ghz, giving a lower bound for intrinsic LL(G) relaxation rates of lambda or G = 85 MHz (alpha = 0.0027) and extrinsic 50 Mhz. Swept frequency measurements indicate the potential for integrated f…
We present a detailed study of the interface morphology of an electro-deposited (ED) Ni/Cu bilayer film by using off-specular (diffuse) neutron reflectivity technique and Atomic Force Microscopy (AFM). The Ni/Cu bilayer has been electro-deposited on seed layers of Ti/Cu. These two seed layers were deposited by magnetron sputtering. The depth profile of density in the sample has been obtained from specular neutron reflectivity data. AFM image of the air-film interface shows that the surface is covered by globular islands of different sizes. The AFM height distribution of the surface clearly sho…
We explore the effect of ionization fraction on the epitaxial growth of Cu film on Cu (111) substrate at room temperature. We compare thermal evaporation, dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS). Three deposition conditions i.e. fully neutral, 50% ionized and 100% ionized flux were considered as thermal evaporation, dcMS and HiPIMS, respectively, for ~20000 adatoms. It is shown that higher ionization fraction of the deposition flux leads to smoother surfaces by two major mechanisms i.e. decreasing clustering in the vapor phase and bi-collision of hig…
The atomic structure and composition of non-interfacial ITO and ITO-Si interfaces were studied with Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The films were deposited by DC magnetron sputtering on mono-crystalline p-type (100) Si wafers. Both as deposited and heat treated films consisted of crystalline ITO. The ITO/Si interface showed a more complicated composition. A thin layer of SiO$_x$ was found at the ITO/Si interface together with In and Sn nanoclusters, as well as highly oxygen deficient regions, as observed by XPS. High energy electron exposure …
Amorphous insulating MoS$_x$ films deposited by magnetron sputtering as a low-index optical coating
P.N. Lebedev Physical Institute of the Russian Academy of Sciences（俄罗斯科学院列别杰夫物理研究所）；National Research University "MPEI"（国立研究型大学莫斯科动力学院）；Moscow Institute of Physics and Technology（莫斯科物理技术学院）
We report on the transition between two regimes from several-atom clusters to much larger nanoparticles in Ar magnetron sputter deposition of WSi2, and the effect of nanoparticles on the properties of amorphous thin films and multilayers. Sputter deposition of thin films is monitored by in situ x-ray scattering, including x-ray reflectivity and grazing incidence small angle x-ray scattering. The results show an abrupt transition at an Ar background pressure Pc; the transition is associated with the threshold for energetic particle thermalization, which is known to scale as the product of the A…
We modify the theory of nanoscale patterns produced by ion bombardment with concurrent impurity deposition to take into account the effect that the near-surface impurities have on the collision cascades. As the impurity concentration is increased, the resulting theory successively yields a flat surface, a rippled surface with its wavevector along the projected direction of ion incidence, and a rippled surface with its wavevector rotated by 90 degrees. Exactly the same morphological transitions were observed in recent experiments in which silicon was bombarded with an argon ion beam and gold wa…
Agent-authored deposition recipes for X-ray multilayer mirrors: schema-bound LLM control of a magnetron sputtering system with reflectivity-verified outcomes
ZJU-UIUC Institute, Zhejiang University（浙江大学中乌联合研究院）；Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校机械科学与工程系）；School of Materials Science & Engineering, Zhejiang University（浙江大学材料科学与工程学院）；School of Mechanical and Electrical Engineering, Liuzhou Polytechnic University（柳州职业技术大学机电工程学院）；SVAC, Zhejiang Saiweike Optoelectronics Technology Co.（浙江赛微科光电科技有限公司）
We report an interesting magnetic behavior of a Co film (thickness ~ 350 Å) grown on Si/Ti/Cu buffer layer by electro-deposition (ED) technique. Using depth sensitive X-ray reflectivity and polarized neutron reflectivity (PNR) we observed two layer structures for the Co film grown by ED with a surface layer (thickness ~ 100 Å) of reduced density (~ 68% of bulk) compared to rest of the Co film (thickness ~ 250 Å). The two layer structure is consistent with the histogram profile obtained from atomic force microscope (AFM) of the film. Interestingly, using PNR, we found that the magnetization in …
The two-dimensional (2D) semiconductor molybdenum disulfide (MoS2) has attracted widespread attention for its extraordinary electrical, optical, spin and valley related properties. Here, we report on spin polarized tunneling through chemical vapor deposited (CVD) multilayer MoS2 (~7 nm) at room temperature in a vertically fabricated spin-valve device. A tunnel magnetoresistance (TMR) of 0.5 - 2 % has been observed, corresponding to spin polarization of 5 - 10 % in the measured temperature range of 300 - 75 K. First principles calculations for ideal junctions results in a tunnel magnetoresistan…
Potentially superhard $W_{1-x}Zr_xB_2$ polymorph hP6-P6$_3$/mmc-$WB_2$ with zirconium doping in the range of x=0.0-0.25 was thoroughly analyzed within the framework of first-principles density functional theory from the structural and mechanical point of view. The obtained results were subsequently compared with properties of material deposited by magnetron sputtering method. All predicted structures are mechanically and thermodynamically stable. Due to theoretical calculations zirconium doping reduces hardness and fracture toughness $K_{IC}$ of $WB_2$. Deposited films are characterized by gre…
We present a molecular dynamics simulation scheme that we apply to study the time evolution of the self-organized growth process of metal cluster assemblies formed by sputter-deposited gold atoms on a planar surface. The simulation model incorporates the characteristics of the plasma-assisted deposition process and allows for an investigation over a wide range of deposition parameters. It is used to obtain data for the cluster properties which can directly be compared to recently published experimental data for gold on polystyrene (M. Schwartzkopf \textit{et al}., ACS Appl. Mater. Interfaces \…
A method for combinatorial sputter deposition of thin films on microparticles is presented. The method is developed for a laboratory-scale magnetron sputter system and uses a piezoelectric actuator to agitate the microparticles through oscillation. Custom-made components enable to agitate up to nine separate batches of particles simultaneously. Due to the agitation, the whole surface of the particles can be exposed to the sputter flux and thus can be completely covered with a thin film. By sputtering a CrMnFeCoNi high entropy alloy target, separate batches of polystyrene microspheres (500 um m…
