Ternary Alloy Composition Research Articles

Self- and Interdiffusion in Ternary Cu-Fe-Ni Alloys

Self- and Interdiffusion in Ternary Cu-Fe-Ni Alloys

Determination of Gold, Silver, and Copper in Gold-Base Alloys by Potentiostatic Coulometry

The working conditions for the simultaneous coulometric determination of 0.5 to 3 mg of gold, silver, and copper with a relative standard deviation of at most ≤0.5% were found in the study of the voltammetric behavior of Au(III), Ag(I), and Cu(II) at a platinum electrode in a 2 M HCl + 0.1 M KCNS solution. Fivefold mass amounts of gold with respect to silver and copper did not interfere with their determination. The three elements can be triply determined in a single portion of a solution using the alternate cathodic and anodic polarization of the electrode ensuring the complete deposition and stripping of Au(0) and Ag(0) and the complete reduction and oxidation of Cu(II) ⇄ Cu(I). The mechanism of current formation due to the chemical reaction of Au(I) disproportionation and its effect on the results of gold determination were studied using the current–time curves. Experimental conditions were proposed to eliminate this reaction. The procedure was used for determining the composition of ternary jewelry alloys containing different amounts of gold, silver, and copper without their preliminary separation.

Development of Sn-Based, Low Melting Temperature Pb-Free Solder Alloys

Low temperature, Sn-based Pb-free solders were developed by making alloy additions to the starting material, 96.5Sn-3.5Ag (mass%). The melting behavior was determined using Differential Scanning Calorimetry (DSC). The solder microstructure was evaluated by optical microscopy and electron probe microanalysis (EPMA). Shear strength measurements, hardness tests, intermetallic compound (IMC) layer growth measurements, and solderability tests were performed on selected alloys. Three promising ternary alloy compositions and respective solidus temperatures were: 91.84Sn-3.33Ag-4.83Bi, 212°C; 87.5Sn-7.5Au-5.0Bi, 200°C; and 86.4Sn-5.1Ag-8.5Au, 205°C. A quaternary alloy had the composition 86.8Sn-3.2Ag-5.0Bi-5.0Au and solidus temperature of 194°C. The shear strength of this quaternary alloy was nearly twice that of the eutectic Sn-Pb solder. The 66Sn-5.0Ag-10Bi-5.0Au-10In-4.0Cu alloy had a solidus temperature of 178°C and good solderability on Cu. The lowest solidus temperature of 159°C was realized with the alloy 62Sn-5.0Ag-10Bi-4.0Au-10In-4.0Cu-5.0Ga. The contributing factor towards the melting point depression was the composition of the solid solution, Sn-based matrix phase of each solder.

Characterization of Cat-CVD grown Si–C and Si–C–O dielectric films for ULSI applications

Si–C films with the Si compositions ranging from 40 to 70% have been grown by Cat-CVD using dimethylsilane [DMSi, Si(CH 3) 2H 2] compounds. Tetraethoxysilane [TEOS, Si(OC 2H 5) 4] and dimethyldimethoxysilane [DMDMOS, Si(CH 3) 2(OCH 3) 2] gas source gave us Si–C–O (C-doped SiO x ) films with wide ternary alloy compositions. The dielectric constant of a Si–C film has been evaluated by C– V measurements (at 1 MHz) using Al/Si–C/n-Si(001)/Cu MIS structure. The relative dielectric constant value of a Si–C film was estimated to be 3.0. The resistivity of the Si–C layer with 1 mm diameter and 0.24 μm thickness was estimated to be more than 24.5 Gohm·cm. These results gave us promising characteristics of Si–C and Si–C–O films grown by alkylsilane- and alcoxysilane-based Cat-CVD.

Characterization of oxide layers on amorphous Mg-based alloys by Auger electron spectroscopy with sputter depth profiling.

Amorphous ribbons of Mg-Y-TM-[Ag] (TM: Cu, Ni), prepared by melt spinning, were subjected to electrochemical investigations. Oxide layers formed anodically under potentiostatic control in different electrolytes were investigated by AES and sputter depth profiling. Problems and specific features of characterization of the composition of oxide layers and amorphous ternary or quaternary Mg-based alloys have been investigated. In the alloys the Mg(KL(23)L(23)) peak exhibits a different shape compared to that in the pure element. Analysis of the peak of elastically scattered electrons proved the absence of plasmon loss features, characteristic of pure Mg, in the alloy. A different loss feature emerges in Mg(KL(23)L(23)) and Cu(L(23)VV). The system Mg-Y-TM-[Ag] suffers preferential sputtering. Depletion of Mg and enrichment of TM and Y are found. This is attributed mainly to the preferential sputtering of Mg. Thickness and composition of the formed oxide layer depend on the electrochemical treatment. After removing the oxide by sputtering the concentration of the underlying alloy was found to be affected by the treatment.

Development of an Au–Dy–Si liquid alloy ion source for focussed ion beam implantation

A liquid metal ion source (LMIS) based on the Au 78.2Dy 8Si 13.8 alloy was developed for focussed ion beam implantation of Dy ions. The mass spectrum of the LMIS shows the presence of Si 2+, Si +, Dy 3+, Dy 2+, Au 2+, Au +, Au 3 2+ and Au 2 + ions. The Au–Dy–Si LMIS shows high stability and long time operational capacity. A simple calculational technique for eutectic compositions of ternary alloys for LMIS is suggested on the base of binary phase diagrams of the elements used.

Effect of carbon on lattice strain and hole mobility in Si1-xGex alloys

Pseudomorphic Si1-x Ge x and partially strain compensated $${\text{Si}}_{1 - x - y} {\text{Ge}}_x {\text{C}}_y $$ layers with different Ge and C fractions have been grown at 500 °C by ultra high vacuum chemical vapor deposition on Si (100) substrates. The degree of strain compensation of the layers has been investigated by high resolution X-ray diffraction and simple application of the linear elasticity theory. The surface morphology of the layers has been characterized by atomic force microscopy. The dependence of Si–Si Raman mode vibrations on strain and composition of binary and ternary alloys have been explained with experimental and theoretically calculated results. The Hall hole mobility is found to increase with decreasing compressive strain or effective Ge content in the layer throughout the temperature range of 120–300 K.

MBE growth of InAs/InAsSb/AlAsSb structures for mid-infrared lasers

The growth by solid source molecular beam epitaxy (MBE) of type-II InAsSb/InAs multi-quantum well laser diodes on InAs has been studied. Strained InAsSb/InAs quantum wells were sandwiched between two AlAs 0.16Sb 0.84 2 μm-thick cladding layers, lattice-matched to InAs. The precise control of the composition of the thick AlAsSb ternary alloy was obtained using a quasi-stoichiometric growth (QSG) method, which requires a determination of the incorporation rate of each element. This rate was obtained from reflection high-energy electron diffraction (RHEED) intensity oscillations. Alloys composition was entirely controlled by Sb 2 flux, suggesting a sticking coefficient close to unity. Mesa-stripe laser diodes processed from the epitaxied structures operated at 3.5 μm in pulsed regime up to 220 K, with a threshold current density of 130 A/cm 2 at 90 K and a peak optical power efficiency of 50 mW/A/facet.

Investigations on Platinum Gauze Surfaces Used in the Manufacture of Nitric Acid

The oxidation of ammonia for the production of nitric acid is a well known process which has been in constant use since the 1890s for the manufacture of fertiliser. Ammonia is oxidised on the surface of a woven or knitted catalyst gauze made of noble metals. Fertiliser production throughout the world partly depends on this technology and research is continuously being undertaken aimed at optimising output and reducing the noble metal loss from the catalysts. Here, some investigations carried out in Ukraine on the surface composition of binary (platinum-palladium) and ternary (platinum-palladiumrhodium) alloys used for the ammonia oxidation process are described. Samples of catalyst received different pretreatments, and their activity was then measured in a laboratory reactor, paying particular attention to the composition of the first few nanometres below the surface. Analysis of the experimental data showed that the role of carbon is different to that of other elements and that the activity of the catalyst is a maximum for carbon concentrations in the range 6 to 10 atomic per cent. It seems most probable than the carbon is present as microcrystals embedded in the alloy and concentrated on the faces of the metal crystals.

Experimental investigations and thermodynamic descriptions of the Ni-Si and C-Ni-Si systems

The binary Ni-Si phase diagram is reassessed and a consistent set of thermodynamic parameters is obtained based on literature data which we could verify experimentally (15 samples involving arc melting, annealing, water quenching, X-ray diffraction (XRD), and differential thermal analysis (DTA)). Applying this description of the Ni-Si system, as well as the descriptions of the Ni-C and Si-C systems available from the literature, preliminary calculations for the C-Ni-Si phase equilibria were made in order to provide guidance in selecting the compositions of decisive ternary alloys. These alloys were subjected to an experimental procedure similar to that employed for the Ni-Si alloys. The XRD and DTA measurements resulting from these ternary alloys provided accurate information on the invariant reaction temperatures in the C-Ni-Si system. Comprehensive comparisons between calculated and measured phase diagrams show that most of the experimental information is satisfactorily accounted for by the present description of the C-Ni-Si system. The liquidus projection and reaction scheme for the whole ternary system are presented.

Melting entropy of Al-based quasicrystals

The melting enthalpies and temperatures of quasiperiodic and periodic phases in Al–Cu–Co, Al–Ni–Co, Al–Ni–Fe and Al–Cu–Fe were measured by differential thermal analysis. From these data the melting entropies of the different phases were derived. The results are discussed in terms of the mutual stability of the quasicrystalline and crystalline phases in these alloy systems, indicating that the entropy of mixing plays an important role for the stabilization of quasicrystalline phases at ternary alloy compositions.

Strong piezoelectric effects in unstrained GaN quantum wells

Optical properties of GaN/AlGaN single quantum well (SQW) and multi quantum well (MQW) structures grown by nitrogen plasma assisted MBE on MOCVD-grown GaN/sapphire have been characterised by low temperature photoluminescence. Photoluminescence (PL) peaks corresponding to emission from very narrow (10 Å wide) SQWs are blue shifted with respect to the bulk GaN emissions but reveal strong red shift for wider SQWs (40 and 60 Å wide). Structural properties of SQW and MQW structures have been characterised by X-ray reciprocal lattice mapping in order to determine the strain conditions and composition of ternary AlGaN alloys. The results clearly demonstrate that in all structures under investigation the ternary (barrier) alloys are fully strained to underlying MOCVD-grown GaN/sapphire substrates. Despite of the fact that GaN quantum wells (QW) are unstrained, photoluminescence experiments clearly reveal the presence of extremely strong electric fields in the QW regions, which can be attributed to the interplay of the piezoelectric-type polarisation in the well and barrier layers due to Fermi level alignment.

X-ray reciprocal lattice mapping and photoluminescence of GaN/GaAlN Multiple Quantum Wells; strain induced phenomena.

Structural properties of GaN/GaAlN multiple quantum wells (MQW) grown by nitrogen plasma assisted MBE on MOCVD-grown GaN/sapphire (GaN pseudosubstrates) have been characterised by X-ray reciprocal lattice mapping to determine the strain and composition of ternary alloys. The results clearly demonstrate that the barriers of GaAlN with up to 17% of aluminium content grown by plasma assisted MBE on GaN are fully strained. Optical properties have been characterised by low temperature photoluminescence. Photoluminescence emission peaks corresponding to the GaN/GaAlN MQW structures revealed strong red-shift with respect to the GaN energy gap. This can be explained by a strong internal electric field present in the QW's which is attributed to a transfer of piezoelectric field due to Fermi-level alignment.

Strong Piezoelectric Effects in Unstrained GaN Quantum Wells

AbstractOptical properties of GaN/AIGaN single quantum well (SQW) and multi quantum well (MQW) structures grown by nitrogen plasma assisted MBE on MOCVD-grown GaN/sapphire have been characterised by low temperature photoluminescence. Photoluminescence (PL) peaks corresponding to emission from very narrow (10 Å wide) SQWs are blue shifted with respect to the bulk GaN emissions but reveal strong red shift for wider SQWs (40 and 60 Å wide). Structural properties of SQW and MQW structures have been characterised by X-ray reciprocal lattice mapping in order to determine the strain conditions and composition of ternary A1GaN alloys. The results clearly demonstrate that in all structures under investigation the ternary (barrier) alloys are fully strained to underlying MOCVD-grown GaN/sapphire substrates. Despite of the fact that GaN quantum wells (QW) are unstrained, photoluminescence experiments clearly reveal the presence of extremely strong electric fields in the QW regions, which can be attributed to the interplay of the piezoelectric-type polarisation in the well and barrier layers due to Fermi level alignment.

Investigation of the Homovalent Impurity in Aluminum to Form Alloys With Enhanced Interconnect Reliability

ABSTRACTDiffusion-induced failures such as stress-induced voiding and electromigration (EM) are a major concern for interconnect metallization in silicon integrated circuits. The addition of solute elements to aluminum interconnects often leads to “blocking” of high diffusivity paths such as grain boundaries and thus to an improvement in the resistance to electromigration failure. This research investigates Al-In, Al-La, and Al-In-La alloys to improve interconnect EM resistance. The choice of these alloying elements is based on the fact that they have negligible solid solubility in aluminum and are homovalent. Lower solubilities may lead to grain boundary stuffing and hence to improved EM resistance. In addition, the homovalency minimizes the adverse effect on the metal resistivity from addition of impurities to aluminum. Multicomponent diffusion principles are used to tailor aluminum-based ternary alloy compositions which would exhibit the multicomponent effect of zero flux planes (ZFPs), or regions in the reaction zone of a diffusion couple where the flux of a component goes to zero. This study involves modeling the occurrence of ZFPs for aluminum in several diffusion couples of Al-In-La, thus limiting the bulk diffusive spreading of aluminum so that the electromigration behavior can be inhibited or eliminated. This paper presents our experimental findings and discusses the modeling approach to determine ternary alloys exhibiting ZFPs.

Ion induced damage in strained CdZnSe/ZnSe quantum well structures

A study of the effects of reactive ion etching on molecular beam epitaxy grown (CdxZn1−xSe/ZnSe) strained quantum well (QW) samples using low temperature photoluminescence reveals a blue shift in the characteristic peak position of the 8 nm QW when exposed to plasmas of H2, D2, or He. Based on experimental results we suggest that this blue shift is a result of ion induced damage interacting with strain present in the as-grown QW. The QW is compressively strained at the interface with additional local strains in the QW lattice due to its random ternary alloy composition. The shallowest QW samples exhibit a peak in the blue shift as a function of bias voltage, with a reduced blue shift seen at high voltages.

Optimized growth of lattice-matched ZnCdSe epilayers on InP substrates

Ternaries and quaternaries of ZnCd(Mg)Se can be grown lattice-matched to InP substrates with band gaps spanning most of the visible range, having potential applications as visible light emitters. The quality of these materials is very sensitive to the surface preparation of InP substrates and the initiation of growth. In this paper, we report the details of the growth initiation of ZnCdSe epilayers on InP substrates. The composition of ternary alloy, and thus the lattice-mismatch to InP, was controlled by adjusting the Zn and Cd fluxes. A fast substrate deoxidation, followed by initial low-temperature growth results in two-dimensional growth and substantial improvements of ZnCdSe epilayers. These results along with observations on the use of InGaAs and InP buffer layers indicate that control of the interface chemistry is essential to obtain high-quality materials.

Optical approaches to determine near-surface compositions during epitaxy

Various algorithms have been proposed for determining the near-surface dielectric function εo of depositing materials from kinetic complex reflectometric or ellipsometric data, even under conditions where the underlying sample structure is unknown. These capabilities are essential for sample-driven closed-loop feedback control of epitaxy, since they allow compositional fluctuations to be detected over nominally vanishingly small thicknesses without the instability inherent in conventional Fresnel analysis. The accuracy of earlier derivative approaches was improved significantly with the development of virtual-interface (V-I) theory, which is based on exact equations instead of exponential-spiral approximations that are valid only for optically thick films. I summarize previous relevant work, assess the accuracy of these derivative methods analytically for the complex normal-incidence reflectance, develop new algorithms by combining earlier approaches, develop a geometric construction that allows relative sensitivities, accuracies, and applicabilities of these algorithms for determining the composition of ternary alloys to be conveniently assessed, and propose a new hybrid V-I–Fresnel method that retains the stability of the V-I approach yet is exact. For ellipsometry the virtual-substrate approximation still represents the best combination of simplicity, speed, and acceptable accuracy.

Vapour phase alloy design of corrosion-resistant overlay coatings

This paper examines the design of hot corrosion-resistant NiCrAl-based coatings by co-deposition from multiple sources. Initial studies examined the deposition of a wide range of ternary alloy compositions by magnetron sputtering or co-evaporation from multiple EB sources. In the magnetron sputtering work a segmented target, consisting of pure Ni, Cr and Al, was used. For the co-evaporation studies, binary and pure element source materials were used. In both deposition procedures new coating compositions were produced by mixing these source materials in the vapour phase. The new coatings were deposited onto pure Al 2O 3 substrates to ensure that no interaction between the coatings and substrate would occur during the corrosion tests. Low temperature hot corrosion of the novel coating compositions was assessed using an ‘ash recoat’ test procedure. Samples were coated in sodium chloride (at 0.75 mg cm −2) every 20 h and exposed in a flowing air-1 % SO 2 equilibrated to an air-SO 2-SO 3 environment, at 750°C for times up to 100 h. Pack aluminised IN738 and uncoated IN738 were included in the test as reference materials and these exhibited classic type II hot corrosion morphologies, as did some of the new coatings tested. Other new coatings resulted in similar deposit chemistries but showed a much lower tendency to form corrosion pits. By modelling the corrosion behaviour along quasibinary sections drawn through the NiCrAl ternary diagram, it has been possible to construct an iso-corrosion contour map at 750°C. These studies have highlighted a new coating composition capable of resisting type II hot corrosion, which on the basis of short time tests offers a six-fold improvement in hot corrosion resistance over conventional NiCrAlY overlay coating compositions as measured using this ‘ash recoat’ test procedure.

Ellipsometric study of metal-organic chemically vapor deposited III–V semiconductor structures

Metal-organic chemical vapor deposition was used to grow epitaxial layers of AlGaAs, GaAs and InGaAs on semi-insulating GaAs substrates. The ternary composition of the thick layers was determined by double-crystal X-ray diffraction (DCXRD). Variable angle spectroscopic ellipsometry was used to characterize several types of structures including relaxed single-component thick films and strained lattice multilayer structures. The thick film characterization included ternary alloy composition as determined by a numerical algorithm and interface quality. The results for the alloy composition were equal to the DCXRD results, to within the experimental errors except for the top layer of a thick AlGaAs film. The strained layer multistructures were analyzed for all layer thicknesses and alloy compositions. For most layers, the thickness was equal to the nominal values, to within the experimental errors. However, in all three In 0.3Ga 0.7As samples, the indium concentration estimated from the relaxed layer's InGaAs algorithm was around 21%, i.e. much lower than the nominal value. This result indicates a shift in the critical points of the dielectric function, owing to strain effects.