Pd Layer Thickness Research Articles

Influence of annealing temperature on structural, optical and electrical properties of AZO/Pd/AZO films

A novel triple-layered transparent conductive film, AZO/Pd/AZO (APA), was deposited via magnetron sputtering on glass substrate at room temperature. The structural, morphological, electrical and optical properties of the APA films were systematically investigated with various Pd layer thicknesses and annealing temperatures in hydrogen atmosphere. The experiment results show that APA films are polycrystalline with a preferred (002) orientation. Comparing with that for the un-annealed films, the resistivity of APA film annealed in hydrogen atmosphere rapidly decreases from 1.84×10−3Ωcm to 4.8×10−4Ωcm, while the transmittance decreased slightly with increasing annealing temperature to 400°C. Optical measurements indicated that the optical band gap (Eg) of APA films varies from 3.37eV to 3.69eV with adjusting annealing temperature from 200°C to 500°C. The very low resistivity of 4.8×10−4Ωcm with a sheet resistance of 45Ω/sq, a transmittance of 83.2% and a figure of merit value of 3.53×10−3Ω−1 were obtained by AZO (50nm)/Pd (7nm)/AZO (50nm) structure after hydrogen annealing at 400°C. These results support that the use of Pd insertion in transparent metal oxide electrode for its hydrogen sensitive property.

Evaluation of Step Resistance in Multilayered Ceramic-Supported Pd-Based Membranes for Hydrogen Purification in the Presence of Concentration Polarisation

In this work, a systematic approach is used to quantify the single-step influence in composite Pd-based membranes on hydrogen permeation in the presence of concentration polarisation. To perform this study, an already developed permeation model is applied to a membrane supported on a five-layered asymmetric porous support. The results are presented in terms of both single-layer influence (calculated using an expression involving the permeation limiting fluxes) and the here introduced Support Resistance Coefficient, SRC, which is a coefficient measuring quantitatively the extent of the driving force in the entire support, analogously to what done for the definition of the Concentration Polarisation Coefficient, CPC. Analysing the membrane behaviour in different conditions of temperature, total feed pressure and Pd-layer thickness, it is eventually shows that, the presence of polarization determine a decreasing effect of the porous support in the considered configuration, i.e., with the selective layer placed on the high-pressure side and the support placed on the permeation one. This conclusion indicates that, for sufficiently thin metal layers, the hydrogen permeation is mostly influenced by concentration polarisation and, thus, the fluid dynamic conditions in the upstream side become a crucial parameter to optimise.

Enhanced interlayer exchange coupling in antiferromagnetically coupled ultrathin (Co70Fe30/Pd) multilayers

We report the studies of magnetization reversal and magnetic interlayer coupling in synthetic antiferromagnetic (SAF) [Pd/Co70Fe30]9/Ru(tRu)/Pd(tPd)/[Co70Fe30/Pd]9 structure as functions of inserted Pd layer (tPd) and Ru layer (tRu) thicknesses. We found the exchange coupling field (Hex) and perpendicular magnetic anisotropy (PMA) can be controlled by both the tPd and tRu, The Hex shows a Ruderman-Kittel-Kasuya-Yosida-type oscillatory decay dependence on tRu and a maximum interlayer coupling strength Jex = 0.522 erg/cm2 is achieved at tPd + tRu ≈ 0.8 nm in the as-deposited sample. As it is known that a high post-annealing stability of SAF structure is required for magnetic random access memory applications, the dependence of Hex and PMA on the post-annealing temperature (Ta) is also investigated. We found that both high PMA of the top Co70Fe30/Pd multilayer is maintained and Hex is enhanced with increasing Ta up to 350 °C for tRu > 0.7 nm in our SAF structure.

Perpendicular Magnetic Anisotropy in CoSiB/Pd/CoSiB Trilayer Thin Films with Varying Pd-Layer Thicknesses.

We investigate the magnetic properties of CoSiB (1 5-Å-thickness)/Pd (Pd thickness = 8, 11, 14, 17, 20, 24, 27, 29 and 33 Å)/CoSiB (15-Å-thickness) trilayer thin films. The CoSiB-layer thickness was fixed to 15 Å, while the Pd-layer thickness was varied from 8-33 Å. In this paper, we present a new type of thin film containing amorphous Co75Si15B10 and Pd. We investigate the magnetic properties of a fabricated CoSiB/Pd/CoSiB trilayer thin film with perpendicular magnetic anisotropy, and determine the correlation between the magnetic properties and the nonmagnetic Pd-layer thickness. With increasing Pd-layer thickness, both the coercivity and the saturation magnetization decreased. Furthermore, the maximum values of the magnetic anisotropy were calculated as 0.3 x 10(6) erg/cc. In order to examine the difference between the in-plane magnetic anisotropy and perpendicular magnetic anisotropy, magnetic force microscopy images of the CoSiB (15-Å-thickness)/Pd (Pd thickness = 8 and 14 Å)/CoSiB (15-Å-thickness) trilayer thin films were obtained.

Dependence of perpendicular magnetic anisotropy and hall resistivity on Pd-layer thickness in CoSiB/Pd multilayer

We investigated the perpendicular magnetic anisotropy and the Hall resistivity of CoSiB/Pd multilayers. The CoSiB/Pd multilayers consisted of CoSiB (7-A thickness) and Pd (Pd thickness tPd = 10, 12, 14, 16, 18, and 20 A), and a CoSiB/Pd bilayer was stacked five times. The coercivity shows oscillating values between tPd = 12 A and tPd = 20 A. The value of the saturation magnetization increased between tPd = 10 A and tPd = 12 A and then decreased after tPd = 12 A. The perpendicular magnetic anisotropy constant depended on the thickness of Pd-layer and the values repeatedly increased and decreased. All CoSiB/Pd multilayers exhibited a positive Hall effect, and the Hall resistivity was not proportional to the magnetic moment.

Fabrication of Pd Micro-Membrane Supported on Nano-Porous Anodized Aluminum Oxide for Hydrogen Separation.

In the present study, nano-porous anodized aluminum oxide (AAO) was used as a support of the Pd membrane. The AAO fabrication process consists of an electrochemical polishing, first/second anodizing, barrier layer dissolving and pores widening. The Pd membrane was deposited on the AAO support using an electroless plating with ethylenediaminetetraacetic acid (EDTA) as a plating agent. The AAO had the regular pore structure with the maximum pore diameter of ~100 nm so it had a large opening area but a small free standing area. The 2 µm-thick Pd layer was obtained by the electroless plating for 3 hours. The Pd layer thickness increased with increasing the plating time. However, the thickness was limited to ~5 µm in maximum. The H2 permeation flux was 0.454 mol/m2-s when the pressure difference of 66.36 kPa0.5 was applied at the Pd membrane under 400 °C.

Development of Palladium-based Oxygen Scavenger: Optimization of Substrate and Palladium Layer Thickness

Oxygen scavenging films based on vacuum deposited palladium layers were developed to remove residual oxygen remaining in food packages after modified atmosphere packaging. Palladium (Pd) was coated on to a range of packaging films and in different thicknesses using magnetron sputtering technology. To improve the substrate surface, an additional silicon oxide (SiOx) layer was also applied to the films before Pd deposition. To determine the oxygen scavenging activity, the scavenger films were placed into an airtight cell, which was flushed with a gas mixture containing 2 vol.% oxygen and 5 vol.% hydrogen. The results showed that the oxygen scavenging rate was strongly dependent on the coating substrate as well as on the Pd deposition thickness. Packaging films such as polyethylene terephthalate, aluminium oxide-coated polyethylene terephthalate, oriented polypropylene and polylactic acid were found to be the most suitable substrates for Pd-based oxygen scavengers. Moreover, it was demonstrated that the intermediate SiOx layer between the substrate and the Pd layer led to a substantial increase in the oxygen scavenging activity rate (up to 33-fold) for all applied packaging films. Additionally, it was shown that the optimal Pd layer thickness for the investigated oxygen scavenging films lies between 0.7 and 3.4 nm. The resulting scavenger films have the potential to scavenge residual headspace oxygen of sensitive foods within a matter of minutes leading to shelf life extension and overall quality improvements. Copyright © 2015 John Wiley & Sons, Ltd.

Correlation between Pd metal thickness and thermally stable perpendicular magnetic anisotropy features in [Co/Pd]n multilayers at annealing temperatures up to 500 °C

We examine highly stable perpendicular magnetic anisotropy (PMA) features of [Co/Pd]10 multilayers (MLs) versus Pd thickness at various ex-situ annealing temperatures. Thermally stable PMA characteristics were observed up to 500 °C, confirming the suitability of these systems for industrial applications at this temperature. Experimental observations suggest that the choice of equivalent Co and Pd layer thicknesses in a ML configuration ensures thermally stable PMA features, even at higher annealing temperatures. X-ray diffraction patterns and cross-sectional transmission electron microscopy images were obtained to determine thickness, post-annealing PMA behavior, and to explore the structural features that govern these findings.

Evaluation of Pd composite membrane for pre-combustion CO2 capture

Carbon capture with hydrogen-selective Pd membranes can be realized as highly integrated process and CO2 can be separated at high pressure without employing environmentally harmful sorption agents. This study investigates the technical viability of using ultrathin Pd/ceramic composite membranes with innovative ceramic-to-metal connections under conditions that are practically interesting for natural gas-fired power stations, i.e. high feed and permeate pressures and high H2 recovery at elevated temperature. The 90% CO2 capture target was well exceeded during a 150 day test in water gas-shifted reformate at 673K. After system stabilization 98% carbon were held back by the membrane while 98% H2 were separated at nominally 99.5% H2 purity. Special attention has been paid to long-term operation effects on the 2–4μm thick Pd layer. These include the development of a striking, cavernous Pd morphology which increases mechanical stability of the composite membrane, a somewhat reduced but steady H2 permeability, and the disappearance of most membrane defects. The latter is attributed to carbon deposits as exit flow analyses point to CO2 reduction preserving effectively membrane selectivity. Altogether, carbon capture with supported Pd membranes projects as feasible from a technological vantage point.

Effects of Pd layer thickness on mechanical properties and microstructures of Sn-3.0 Ag-0.5 Cu solder joints

In order to investigate effects of Pd layer thickness on the mechanical properties and microstructures of Sn-3.0 Ag-0.5 Cu solder joints, three different Pd layers, i.e., 0.05, 0.1, 0.15 µm, were employed on the electroless nickel immersion gold [ENIG, Ni-P(5 µm )/Au(0.08 µm)] surface finished flame retardant type 4 (FR4) printed circuit board (PCB) substrates. Our studies showed that the addition of Pd layer in ENIG treatment, i.e., ENEPIG, enhanced the bonding strength of solder joints by reducing the formation of intermetallic compounds (IMCs), (Cu, Ni)6Sn5 and (Ni, Cu)3Sn4. The different failure modes were also observed – the crack propagation occurred along the interface between P-rich Ni layer and Cu layer in 0.05 µm Pd specimens while specimens with 0.1 µm and 0.15 µm Pd layers showed the crack propagation proceeded mostly inside solders. In this study the effects of Pd layer thickness in ENEPIG surface finish on the bonding strength of solder joints were investigated by means of drop test and ball shear test, followed by observation of microstructures and interfaces using a scanning electron microscope (SEM) and an energy dispersive spectrometer (EDS).

Evaluation of mechanical properties of low-Ag ball grid array solder joints using a high-speed ball shear test

Solder joints of Sn–1.0Ag and Sn–1.0Ag–0.1Ce on electroless nickel/electroless palladium/immersion gold (ENEPIG) were studied and mechanically evaluated using a high-speed shear test. The effect of Pd thickness in ENEPIG on the reliability of solder joints was evaluated after multiple reflows. Microstructural observations of the solder joint interfaces and fractures after shear tests are shown. For comparison, conventional SAC305 Pb-free solder was also mechanically evaluated under the same conditions. By adding a thin Pd layer in ENEPIG surface finish, the intermetallic compound (IMC) layer’s morphology of SAC305 change from needle type (as Pd thickness=0μm) to scallop type (as Pd thickness=0.1μm). While the intermetallic compounds (IMCs) layer’s morphology of 1.0Ag solders change from facet type (as Pd thickness=0μm) to needle type (as Pd thickness=0.1μm). ENEPIG with thicker Pd layers was suitable for 1.0Ag solders during high speed shear test whereas conventional SAC305 showed the highest shear strength with an ENIG surface finish.

Pd distribution of switchable mirrors based on Mg–Y alloy thin films

Pd-capped magnesium–yttrium alloy switchable mirrors were found to have high switching durability of over 10,000 cycles between reflective and transparent states. However, the durability decreased with the decreasing Pd thickness. Switchable mirrors with various Pd thicknesses were then prepared by a direct-current magnetron sputtering method, and the degradation in durability was studied by observing the distribution of each element of the switchable mirrors from the film surface to the substrate. X-ray photoemission spectroscopy and transmission electron microscopy showed that Pd with a short sputtering time (corresponding to layer thickness of 3nm) resulted in surface oxidation of Mg and Y, and no Pd was present at the surface. The deposited Pd was alloyed with the Mg–Y layer and after taking the sample out from the vacuum chamber a Pd-rich layer appeared between the surface oxides and the Mg–Y layers. With increasing deposition time, a Pd layer was formed on the oxide layer and the Pd layer thickness increased. The mirror with switching durability of over 10,000 cycles had a sufficiently thick Pd top layer of ~7nm and a very thin oxide layer. This thick Pd layer is believed to be the reason for the high switching durability.

Gold and palladium embrittlement issues in three-dimensional integrated circuit interconnections

This study reports the re-emergence of the classical Au and Pd embrittlement problems in micro joints in three-dimensional integrated circuits (3D ICs) applications. Our results indicate that (Au,Pd,Ni)Sn4 can form a continuous layer across entire joints even if the Au and Pd layers are very thin. This morphology is detrimental to the joint reliability. This study shows that it is practically impossible to avoid these embrittlement problems simply by reducing the thickness of Au or Pd layers when the micro joints are smaller than 10μm. An effective solution to eliminate such embrittlement problems is to introduce relatively large amounts of Cu to the micro joints.

Nanorods of Co/Pd multilayers fabricated by glancing angle deposition for advanced media

Perpendicular anisotropy magnetic nanorods composed of Co/Pd multilayers have been successfully fabricated by glancing angle deposition (GLAD) in a planetary sputtering system. Co and Pd layer thickness, ratio, and bilayer number were optimized for both normal and GLAD depositions. Scanning electron micrographs estimated the nanorods to be about 12 nm in diameter. M-H loops showed that the coercivity for the GLAD nanorods increased from 1.3 kOe for the normally deposited continuous films to 2.9 kOe for the GLAD nanorod array, a 123% increase.

Spin wave excitations in exchange-coupled [Co/Pd]-NiFe films with tunable tilting of the magnetization

Brillouin light scattering was applied to measure the evolution of spin waves in exchange-coupled [Co/Pd]-NiFe films with out-of-plane/in-plane magnetic anisotropy. Tunable tilting of the magnetization has important effects on the spin wave frequency gap: a substantial increase is observed with decreasing the soft NiFe thickness, while seemingly insignificant tilting angles cause a strong reduction with respect to a film with only the hard [Co/Pd] component. The spin wave frequency is reproduced also in samples, with increased thickness of the upper Pd layer, where a sudden modification in the tilting at the hard/soft interface is caused by the weakening of interlayer exchange.

Temperature and Co thickness dependent sign change of the anomalous Hall effect in Co/Pd multilayers: An experimental and theoretical study

The anomalous Hall effect in ultra-thin {Co0.3 nm/Pd0.5 nm}n multilayers has been investigated recently with respect to surface and interface contributions [Guo et al., Phys. Rev. B 86, 104433 (2012)]. In this work, we observe a Co thickness and temperature dependent sign change also for {Co0.20–0.55 nm/Pd1.5nm or 1.8 nm}9x multilayers, e.g., in layer stacks with considerably thicker Pd layers and hence lower resistivity. The thickness dependent behavior can be reproduced by ab initio calculations of the Hall conductivity, for which only interfacial and bulk contributions play a role.

Optical response of WO3 nanostructured thin films sputtered on different transparent substrates towards hydrogen of low concentration

The gasochromic response of WO 3 nanostructured films coated with a catalytic Pt or Pd layer on different transparent substrates upon exposure to H 2 gas was investigated. WO 3 nanostructured films with 500 nm thickness were coated with a 25 Å thick Pt or Pd layer. The films were prepared on quartz, glass, indium-doped tin oxide (ITO) and fluorine-doped tin oxide (FTO) conductive glass. The nanostructured WO 3 was deposited by RF magnetron sputtering, and the Pt or Pd layer was deposited by DC sputtering. Characterization of the film revealed that the WO 3 was deposited as nanoscale grains of varied size depending on the substrate. WO 3 grains on quartz and glass were 30–40 nm in size. WO 3 grain sizes on ITO and FTO were 40–60 nm and 300–500 nm, respectively. The WO 3 films were observed to show strong gasochromic response, with absorbance changes measured in the Vis-NIR (500–1100 nm) range. The cumulative absorbance response towards H 2 is the highest and more stable for Pd/WO 3 films on quartz, glass and ITO, compared to the FTO substrate. The gasochromic effect was also stronger in Pd/WO 3 films compared to Pt/WO 3 films.

Influence of layer thickness on the structure and the magnetic properties of Co/Pd epitaxial multilayer films

Co/Pd epitaxial multilayer films were prepared on Pd(111)fcc underlayers hetero-epitaxially grown on MgO(111)B1 single-crystal substrates at room temperature by ultra-high vacuum RF magnetron sputtering. In-situ reflection high energy electron diffraction shows that the in-plane lattice spacing of Co on Pd layer gradually decreases with increasing the Co layer thickness, whereas that of Pd on Co layer remains unchanged during the Pd layer formation. The CoPd alloy phase formation is observed around the Co/Pd interface. The atomic mixing is enhanced for thinner Co and Pd layers in multilayer structure. With decreasing the Co and the Pd layer thicknesses and increasing the repetition number of Co/Pd multilayer film, stronger perpendicular magnetic anisotropy is observed. The relationships between the film structure and the magnetic properties are discussed.

Hydride formation in single palladium and magnesium nanoparticles studied by nanoplasmonic dark-field scattering spectroscopy.

Scrutinizing functional nanosystems and relating details in their size, chemistry, and geometry to functionality remains a significant experimental challenge. Following the concept of indirect nanoplasmonic sensing (INPS), the exploitation of truncated Au nanocones with functionalized tips, nanofabricated in a one step, are used as single nanoplasmonic sensors for dark-field scattering spectroscopy measurements of the hydride formation Au in single Pd and Mg nanoparticles.

Oxidation Behavior at the Ni–W and ${\rm CeO}_{2}$ Interface With and Without Pd Over Layer

The interface between the cube textured Ni-W substrate, both bare and Pd-buffered, and the CeO2/YSZ buffer layer structure-required to growth YBCO coated conductors-samples have been subjected to different oxidizing conditions and have been investigated with different techniques: X-ray diffraction (XRD), X-ray absorption and Auger electron spectroscopy. Due to the Ni-Pd interdiffusion, the presence of a Pd over layer significantly modifies the substrate surface composition and the substrate oxidation mechanism. Depending on the Pd layer thickness, the formation of NiO can be completely prevented while the formation of ternary oxides and of W oxide is favored. Moreover, the Pd layer affects the extension of interface between the substrate and the CeO2 layer and the portion of uncontaminated CeO2.