Au-Sb Alloys Research Articles

Examination of characteristic parameters of Zn/n-Si junction depending on electron radiation applied at different doses

In this work, we have studied the electrical characteristics of Zn/n-Si/Au-Sb Schottky diodes before and after different doses (25, 50 and 75 Gray) of electron-irradiation at room temperature. The ohmic contact has been made on n-Si crystal with Au-Sb alloy. The rectifier contact was sputtered Zinc metal on n-Si by using DC magnetron sputtering. The I–V measurements of these diodes performed by the use of a KEITLEY 487 Picoammeter/Voltage Source and the C–V measurements were performed with HP 4192A (50–13 MHz) LF Impedance Analyzer at room temperature and in dark. Experimental results showed that the values of the ideality factor obtained from I to V measurements increased and the values of the barrier height obtained from I to V and C–V measurements decreased after electron-irradiation.

The effects of different doses of electron radiation on the electrical characteristics of ZnO interfacial Zn/n-Si junction

In this work, we have investigated the electrical characteristics of Zn/ZnO/n-Si/Au-Sb Schottky diodes before and after different doses (25 and 50 Gray) of electron-irradiation at room temperature. Initially, the ohmic contact has been made on n-Si semiconductor with Au-Sb alloy. After this process the ZnO thin film was grown on n-Si semiconductor by using RF magnetron sputtering system, and then the contact area is determined by sputtered Zn metal to surface of ZnO in DC sputtering system at about 10-6 Torr. The characteristic parameters of the junction such as ideality factor and barrier height values are calculated from I to V measurements and the carrier concentration, Fermi energy, diffusion potential, and barrier height values are calculated from reverse bias C-2–V measurements at various frequencies and room temperature. The I–V and C–V measurements of these diodes performed at room temperature and in dark. Experimental results showed that the values of the ideality factor increased and barrier height from forward-bias I–V measurements decreased and diffusion potential and the values of the barrier height obtained from reverse-bias C–V measurements decreased after electron-irradiation. However, changes in the characteristic parameters of the ZnO interfacial layer diode in 25 Gray of electron-irradiation were found to be less than those of the 50 Gray of electron-irradiation.

The protection from the effects of gamma rays of metal-semiconductor diodes by means of ZnO thin interface layer

In this study, the protective effects of Zinc oxide (ZnO) interfacial layer in the Zn/n-Si rectifying contacts against gamma radiation were investigated. In the fabrication of the diodes, n-type Si is used as a semiconductor. First, an ohmic contact is made by using Au–Sb alloy on the polished surface of the n-Si. Afterwards, the ZnO thin film is grown on the n-type Si semiconductor substrate by the RF magnetron sputtering technique. The structural properties of ZnO thin films are investigated by x-ray diffraction (XRD) measurements. It is found that ZnO films are polycrystalline. Current-voltage (I–V) measurements of Zn/n-Si/Au–Sb and Zn/ZnO/n-Si/Au–Sb diodes which are fabricated under laboratory conditions are taken at room temperature in the dark. The basic electrical parameters such as ideality factor (n), barrier height (Φb), series resistance (Rs), rectifying ratio (RR) and interface state density (Nss) of diodes are calculated from the forward bias I–V characteristics. To examine the effects of gamma radiation on the electrical parameters, the diodes are exposed to gamma rays using barium-133, americium-241, and cobalt-60 gamma sources. After irradiation, I–V measurements of diodes are taken again, the characteristic parameters are calculated and the results are compared with the previous ones.

Effects Of the γ- radiation on the electrical characteristics of the Au/n-Si/Au-Sb Schottky diode

In this study is investigated of effects of the γ-radiation on current-voltage (I-V) and capacitance-voltage (C-V) characteristics of Au/n-Si/Au-Sb Schottky diode at room temperature. Initially, the ohmic contact has been made on n-Si crystal with Au-Sb alloy. Then, the rectifier contact is made by evaporation Au metal diameter of about 1.0 mm to the other surface of n-Si in turbo molecular pump at about 10-7 Torr. The I–V measurements of this diode performed by the use of a KEITLEY 487 Picoammeter/Voltage Source and the C–V measurements were performed with HP 4192A (50–13 MHz) LF Impedance Analyzer at room temperature and in dark. Then, this diode was subjected to γ-radiation, and I-V and C-V measurements were taken again. Consequently, examines the difference between these two measurements.

Superconductivity at the highest transition temperature of 8.1 K in a simple cubic AuxSb1−x−yTey alloy system synthesized under high pressure

We have investigated superconductivity and structure in a gold–antimony–tellurium ternary alloy system (AuxSb1−x−yTey) synthesized under high pressure. We found that Au0.125Sb0.75Te0.125 and AuSb6Te when crystallized in simple cubic structures (α-Po type), which are reported to be semiconductors above 20 K, are superconductors with a transition temperature (Tc) of 6.7 K. The structure and Tc are mapped on an Au–Sb–Te triangular diagram. A β-Po-type rhombohedral structure appears before the crystal structure changes from As type (Sb) to α-Po type. Superconductivity is observed in the β-Po-type structure as well as in the α-Po-type structure. Tc increases with decreasing Te concentration toward the Te-free Au–Sb end of the diagram. A Tc of 8.1 K was achieved for the Au–Sb alloy with a typical composition of Au0.15Sb0.85. This Tc value is the highest among materials with the α-Po-type structure under ambient pressure. Our Au0.125Sb0.75Te0.125 sample exhibits a weak metallic behavior in resistivity. The discrepancy in the normal state resistivity behaviors between the previous study and ours must originate from a difference in the number of lattice defects in the samples.

Lead-free solder alloys: Thermodynamic properties of the (Au + Sb + Sn) and the (Au + Sb) system

The thermodynamic properties of liquid (Au–Sb–Sn) alloys were studied with an electromotive force (EMF) method using the eutectic mixture of KCl/LiCl with addition of SnCl2 as a liquid electrolyte. Activities of Sn in the liquid alloys were measured at three cross-sections with constant molar ratios of Au:Sb=2:1, 1:1, and 1:2 with tin in the concentration range between 5at.% and 90at.% from the liquidus of the samples up to 1073K. The integral Gibbs excess energies and the integral enthalpies at 873K were calculated by Gibbs–Duhem integration. Additionally liquid Au–Sb alloys have been measured at 913K with the EMF method as no reliable data for the Gibbs excess energies have been found in literature. The eutectic mixture of KCl/LiCl with addition of SbCl3 has been used as an electrolyte for the measurements. The Gibbs excess energies from the (Au+Sb) system were necessary for the integration of the thermodynamic properties of the ternary (Au+Sb+Sn) system.

Synthesis of Light Emitting Ge Nanocrystals by Reactive RF Sputtering

In this work we report the results of the synthesis, structural and optical characterization of SiO2/Ge/SiO2heterostructures by reactive RF sputtering. The SiO2films were grown by reactive sputtering employing a plasma mixture of oxygen and argon. The Ge layer was grown employing an Ar atmosphere. The samples were prepared on p-type Si (1 1 1) substrates by reactive sputtering. The effect of the partial pressure of oxygen on the electronic properties of the heterostructure is reported[1]. Structural characterization was carried out by grazing angle X-ray difraction. Surface roughness was quantified by atomic force microscopy. The presence of Ge nanocrystals (Ge-NCs) was evidenced by X-ray diffraction. The vibrational properties were studied by Raman spectroscopy. The Raman spectra showed modes associated to germanium indicating the formation of low dimensionality germanium particles embedded within a SiO2matrix. Photoluminescence emission is observed around ~1.7 eV and it is associated to the quantum confinement of carriers in Ge-NCs. Ohmic contacts were deposited using a van der Pauw geometry employing an a AuSb alloy for the contacts. Temperature dependent Hall (T-Hall) measurements were done between 35 K and 150 K, using the van der Pauw method. The results indicated low resistivity values that could be explained due to some variable range hopping conduction mechanism.

Hot electron induced cathodic electrochemiluminescence at AuSb alloy electrode for fabricating immunosensor with self-assembled monolayers

Thin antimony oxide covered AuSb alloy electrode was firstly found to be an excellent cold cathode for generating hot electrons during cathodic pulse polarization. Owing to the injection of hot electrons and the subsequent generation of hydrated electrons, fluorescein iso-thiocyanate (FITC) that cannot be excited in common ECL was cathodically excited at the alloy electrode. Self-assembled thiol monolayers were formed on the electrode surface due to the presence of Au in the alloy, to which strepavidin was covalently bound, and then biotinylated antibody was immobilized through the strepavidin–biotin interaction. As a simple model, an immunosensor for the detection of human IgG (hIgG) using FITC as labeling agent was fabricated. ECL signals were responsive to the amount of hIgG bounded to the immunosensor. The ECL intensity was linearly changed with the logarithm of hIgG concentration in the range of 1.0–1000 ng mL −1, and the detection limit was ca. 0.3 ng mL −1 (S/N = 3). The proposed immunosensor showed a broad linear range (three magnitudes), good reproducibility and stability, which is promising in detecting FITC-based labels in various types of bioaffinity assays.

Phase diagrams in nanometer-sized alloy systems

The phase diagram in nm-sized Au–Sb alloy system has been studied by transmission electron microscopy. With decreasing system size, the increase of solid solubilities in solid solution or intermetallic compounds are significantly enhanced. With a further decrease in the system size, the pure substance continuously changes into solid solution, a highly disordered ultra-fine grain nanostructure and then to intermetallic compound as the solute concentration increases. The formation of the highly disordered ultra-fine grain nanostructures may be related to the low heterogeneous nucleation probability.

Surface barrier detectors using aluminum on n- and p-type silicon for α-spectroscopy

We describe the method by which surface barrier detectors (SBD) can be constructed from p- and n-type high-purity silicon (Si), with aluminum (Al) as a rectifying contact. This material has as properties: firm adhesivity to silicon, excellent light-tightness and low stopping power for charged particles, that are ideal for the entrance window. For the ohmic contact, we have used different metals: Al, gold (Au) plus antimony (Sb) mixture and AuSb alloy, with appropriate chemical treatment during the fabrication process. Electrical measurements have given the desired properties for the detection of charged particles. Unencapsulated SBDs show a low leakage current and an excellent long-term stability both in air and in vacuum. The energy resolution for the 5.486 MeV α-particle varies from 17 to 22 keV for detectors with sensitive area 20–80 mm 2.

Hydrothermal characterization of the West Gore Sb-Au deposit, Meguma Terrane, Nova Scotia, Canada

The West Gore Sb-Au deposit is anomalous in the Megurea terrane of Nova Scotia because of its enrichment in Sb, a metal that is essentially absent from other Megurea gold deposits. The deposit is hosted by graphitic and sulfide-bearing slates of the lower Paleozoic Halifax Formation that were deformed into a northeast-trending, upright, closed syncline and metamorphosed to the greenschist facies during the regional Acadian orogeny (ca. 400 Ma). Mineralized veins at the deposit define a single structure trending 110 degrees that probably formed the dextral component of a conjugate shear system as part of regional, northwest-directed compression. The veins crosscut a penetrative regional schistosity (S 1 ) in the host slates and vein formation is constrained by (1) the presence of cleaved wall-rock slates in the veins, (2) vein-related sulfides overgrowing the S 1 fabric in wall-rock fragments, and (3) a 370 Ma 40 Ar/ 39 Ar plateau age for hydrothermal muscovite. Mineralization occurs as stibnite, native antimony, aurostibnite, Au-Sb alloys, and Au-Sb-O phases in vein quartz with associated Fe, As, Pb, Zn, Cu sulfides and chlorite-carbonate gangue; wall-rock alteration is variably developed as narrmv zones peripheral to veins enriched in sericite, calcite, sulfides, tourmaline, and chlorite. Early stages of mineralization are constrained to maximum temperatures of 495 degrees C from arsenopyrite geothermometry, but lower temperatures are recorded by chlorite geothermometry (350 degrees -390 degrees C). Textures of vein quartz include comb and plumose varieties with a bimodal grain size and also a coarser, anhedral quartz. Fluid inclusion studies indicate that the fluid was a mixed H 2 O-NaCl-CaCl 2 -CO 2 -CH 4 type and that fluid unmixing occurred, albeit in minor amounts. Thermometric measurements reveal maximum T h of 375 degrees C and a range of salinities (0.4-28.1 wt % NaCl equiv). The volumetric properties of fluid inclusions reflect cycling of fluid pressures with supralithostatic pressures (to 4-5 kbars P fluid ) recorded by the presence of H 2 O-CO 2 inclusions (to 20 mole % CO 2 ) which are interpreted to have resulted from fluid-rock interaction. Subsequent reduction in fluid pressures (to ca. 2 kbars) resulted in decreasing amounts of CO 2 (<1-2 mole %) and fluid unmixing that generated higher and lower salinity trends observed in T h -salinity plots.Vein-forming fluids are characterized by delta 13 C (sub Sigma C) = -19.5 to -22.6 per mil, delta 18 O (sub H 2 O) = 9 to 15 per mil, delta D = -42 to -64 per mil, and delta 34 S (sub H 2 S) = 9.7 to 10.3 per mil based on analysis of calcite, quartz fluid inclusion extracts in quartz and stibnite. Vein tourmaline associated with stibnite has 87 Sr/ 86 Sr measured of 0.71707 to 0.72284. These data are consistent with a metamorphic origin for the fluid with local inheritance of C and S isotope signatures from interaction of the ore fluid with graphite and sulfide wall-rock slates of the Halifax Formation.The West Gore deposit originated from infiltration of metamorphic-derived fluids generated during the waning stages of the Acadian orogeny contemporaneous with generation and emplacement of felsic and mafic magmas. The mineralizing fluids were focused to higher crustal levels (P fluid = ca. 2 kbars) where brittle-ductile conditions prevailed and veins were localized to the dextral component of a conjugate shear system related to movement along a major dextral strike-slip fault or shear zone (Cobequid-Chedabucto fault system). Deposition of vein constituents resulted from a decrease in temperature and changes in fluid chemistry (decrease in f (sub S 2 ) and f (sub O 2 ) ) induced by fluid unmixing and interaction with the wall rock. Lithogeochemistry of the local stratigraphy does not indicate any regional enrichment in Sb, Au, or other metals. The occurrence of the stibnite may, therefore, reflect either telescoping of metals in a Au-W-Sb province or enrichment of Sb in the source area or fluid conduit relative to other Meguma gold deposits.

Effect of cluster size on phase stability in nm-sized Au-Sb alloy clusters

The effect of cluster size on the phase stability in nanometre (nm)-sized Au-Sb alloy clusters has been studied by means of transmission electron microscopy (TEM), in order to see the difference in the phase stability between a bulk material and the corresponding nm-sized cluster. When the cluster size is reduced below approximately 6 nm in mean diameter, it is difficult to form distinct interfaces between two different phases (i.e. solid solution and AuSb 2) in the interior of individual Au-Sb alloy clusters. Analytical electron microscopy using an electron probe of approximately 1 nm in diameter revealed that the solid solubility of antimony in a few nm-sized gold clusters increases by at least one order of magnitude compared to that for the corresponding bulk material.

Low-temperature interface reactions in layered Au/Sb films: In situ investigation of the formation of an amorphous phase.

Photoelectron-spectroscopy methods combined with electrical-resistance measurements were employed to study the effects of intermixing at Au/Sb interfaces at low temperatures. For the purpose of characterizing the growth processes of the intermixed phase on a ML scale, Au/Sb bilayers (layer thicknesses ${\mathit{D}}_{\mathrm{Au}}$=0.5--75 ML and ${\mathit{D}}_{\mathrm{Sb}}$=150 ML) were evaporated at 77 K and the different in situ techniques allowed a comparison to vapor-quenched amorphous ${\mathrm{Au}}_{\mathit{x}}$${\mathrm{Sb}}_{100\mathrm{\ensuremath{-}}\mathit{x}}$ alloys. For Au thicknesses between 0.5 and 0.9 ML, a change from a semiconducting to a metallic behavior of the samples has been detected, as indicated by the development of a steplike photoelectron intensity at the Fermi level. Evidence has been found that for Au coverages \ensuremath{\le} 6 ML chemical reactions at the Au/Sb interface occur, leading to the formation of a homogeneously intermixed amorphous layer with a maximum thickness of about 2.3 nm and Au concentrations as high as x\ensuremath{\approxeq}80 at. %. This latter value corresponds to the limiting Au content where amorphous alloys can be prepared at low temperature (0 at. % \ensuremath{\le}x\ensuremath{\le} 80 at. %). For nominal coverages beyond 6 ML polycrystalline Au films were formed. Consequently, Au/Sb multilayers with sufficiently small modulation lengths, which were prepared at 130 K by ion-beam sputtering, were observed to grow as a homogeneous amorphous phase over a broad range of compositions, as evidenced by in situ resistance measurements and by comparing the obtained crystallization temperatures to those of vapor-quenched amorphous alloys. Variation of the deposition temperature ${\mathit{T}}_{\mathit{s}}$ revealed that an amorphous interface layer is only formed for ${\mathit{T}}_{\mathit{s}}$\ensuremath{\le} 220 K. This is consistent with the fact that for multilayers with large modulation lengths containing unreacted polycrystalline Au and Sb layers, long-range interdiffusion is found to set in at temperatures above 230 K. This interdiffusion, however, results in the formation of polycrystalline Au-Sb alloys.

A Thermodynamic Investigation of Liquid Gold-Antimony Alloys

The enthalpies of mixing of liquid Au-Sb alloys were determined between 906 and 1028 K giving Δ mix H° m = x Sb x Au (−11.234 −1.1078 x Sb + 5.713 x Sb 2 ) kJ mol −1 . The minimum was found at x Sb = 0.45 with Δ mix H° m = −2.62 ± 0.2 kJ mol −1 contrary to published measurements on liquid Au-Sb alloys. The limiting partial molar enthalpy of Au in Sb at 935 K was measured to Δ mix h° m (Au, liq, in ∞Sb, liq) = −6.05 ± 0.4 kJ mol −1 . The enthalpy of formation of the solid compound AuSb 2 determined at 298 K by solution calorimetry in liquid Sb, Δ f H° m (AuSb 2 ) = −5.40 ± 0.6 kJ mol −1 , is found in fair agreement with literature data. DTA measurements were performed on the Au-rich part of the liquidus and a new liquidus curve is suggested between Au and the eutectic concentration. The eutectic point was found at 63.07 ± 0.25 K and x Sb = 0.350

Thermodynamic investigation of the solid and liquid AuSb alloys

The heat content of solid and liquid AuSb 2 compound was measured from 298 K to T (375–963 K) on heating (drop method) with the help of a Tian-Calvet calorimeter. The heat capacity of the liquid compound as well as its enthalpy of fusion were deduced. The enthalpy of the liquid decreases strongly when temperature increases between the melting point and 831 K. The enthalpy of formation of the AuSb melts was also determined by direct reaction calorimetry at 916 K with respect to concentration. The enthalpy of mixing is weakly negative in the whole range of concentration ( min f = −3·47 kJ/mol at x Au = 0·775) in agreement with the results of Béja at 923 K. disagree with the much more negative earlier data of Kameda et al. and of Hino et al. by emf and vapor pressure measurements. Finally, the liquid/Au(cr) phase boundary determined at 916 K from the break in the h f ( x Au) curve agrees well with the phase diagram calculated by Okamoto and Massalski but not with their experimental results.

Observation of doubly-charged dimer ion emission in liquid-metal-ion sources

Liquid-metal-ion sources (LMIS's) emit atomic and cluster ions. In the mass analysis of LMIS's using Au-Sb and Pt-Sb alloys, the doubly-charged dimer ions Sb 2+ 2 are observed as well as the doubly-charged diatomic ions AuSb 2+ and PtSb 2+. The flux abundance of Sb 2+ 2 in Sb + +Sb 2+ 2 for a Au-Sb alloy is approximately 20%, which is larger by one order of magnitude than that for a Pt-Au alloy. It is predicted that the stability of cluster ions is strongly affected by the electrostatic field near the ion emitter. The formation mechanism of M 2+ 2 ions is discussed using mass spectra and energy distribution curves.

119Sb Mossbauer study on quenched-in vacancies in gold

119Sb emission Mossbauer spectra are measured for very dilute, quenched Au-Sb alloys. Two distinct satellite lines observed after quenching and subsequent annealings were assigned to vacancy-solute pairs and vacancy-solute clusters, respectively. Their electronic state and behaviour are investigated during annealing. The effect of oxidation was also examined and separated from that of vacancy-solute interactions in the analysis.

Magnetic Susceptibility and Electronic Structure in Metallic and Nonmetallic Liquid Cesium‐Gold and Cesium‐Antimony Alloys

AbstractMeasurements of the concentration and temperature dependence of the magnetic susceptibility K of liquid CsAu and CsSb alloys are reported. At the stoichiometric compositions CsAu and Cs3Sb, respectively, K exhibits a pronounced diamagnetic minimum of ‐81 · 10−6 emu · mol−1 for CsAu and ‐ 85 · 10−6 emu · mol−1 for Cs3Sb. It is shown that magnetic susceptibility provides a good means for the study of chemical bonding and electronic structure in these liquids. In the nonmetallic electrical transport regime the data are discussed in terms of various models for the electronic structure of metal atoms dissolved in a more ionic or more semiconducting liquid alloy. In the case of CsAu alloys a complete description of the change of the nature of electronic states from nonmetallic to metallic behaviour can be deduced from the measured K‐values. The temperature dependence of K for CsSb alloys near the composition Cs3Sb gives indication for a transport mechanism typical of liquid semiconductors.

Ａｕ系共晶合金を用いた薄膜溶融接合について

As for diamond heat sinks, the properties of Au eutectic alloys used for bonding a semiconductor chip to a diamond are investigated, and then, film-soldering method is studied in which a semiconductor chip is soldered to a metallized diamond substrate evenly under small load with low melting alloyed film.As soldering materials, Au-Sb, Au-Sn and Au-In alloys are selected and their properties, viz. thermal conductivity, electric resistance, hardness and tensile strength, are investigated. In all alloys, their eutectic alloys have similar properties, and in Au-Sb alloy, which has no alloy phase in hypo-eutectic region, it can improve its properties when its composition becomes Au-rich from the eutectic composition.In soldering experiments, Au-Sb alloy is mainly used and GaAs chips and Pyrex glass, as model specimens, are soldered in an atmosphere of H2 gas. The effects of temperature, time, load, film thickness, film structure, and film composition on the soldering strength are investigated, resulting that the conditions for assuring the appropriate soldering are defined. From the XMA analysis of alloyed film's composition, together with above results, it is found that the rate of soldering reaction is controlled by the interdiffusion of Sb into Au solid phase.In comparison with above results, similar investigation is carried out using Au-Sn alloy.