AuZn Alloy Research Articles

ZnO nanorods grown by a Pulsed Laser Deposition process

ABSTRACTZnO nanorods were synthesized by a hot-wall type pulsed laser ablation process. At temperatures 500∼800°C, ZnO thin films and wrinkles were synthesized. Above 800°C, vertically aligned ZnO nanorods were grown on the Si and sapphire substrate without any catalysts. The range of diameter was 100∼300nm. When Au catalyst were deposited on the substrate prior to the deposition, the process range of ZnO nanorod become wider and the diameter of ZnO narrower. Especially, ZnO could be grown selectively along the pattern of Au catalyst with the aid of Au-Zn alloy.

The effect of Cr barrier on interfacial reaction of Au/Zn/Au/Cr/Au contacts to p-type InGaAs/InP

Alloy-type metal is widely used to reduce contact resistance in optoelectronic devices. Among the alloy-types, Au/Zn is one of the most common metallization systems. In this paper, we studied the alloy morphology of p-InP/p-InGaAs/Au/Zn/Au/Cr/Au systems. We found that the amount of Au–Zn alloy depended upon the thickness of the Cr layer. When Cr thickness was reduced to 135 Å, both Au-rich and GaAs-rich excessive compound formation started to occur. The Au diffusion punched through the InGaAs layer and penetrated into the InP. Comparison of Au/Zn/Au and Au/Zn/Au/Cr/Au suggested that the top Au layer maybe very influential during the alloy reaction. The Au–Zn alloy was significantly less in the Au/Zn/Au than that in the Au/Zn/Au/Cr/Au.

The effect of Cr barrier on interfacial reaction of Au/Zn/Au/Cr/Au contacts to p-type InGaAs/InP

Alloy-type metal is widely used to reduce contact resistance in optoelectronic devices. Among the alloy-types, Au/Zn is one of the most common metallization systems. In this paper, we studied the alloy morphology of p-InP/p-InGaAs/Au/Zn/Au/Cr/Au systems. We found that the amount of Au–Zn alloy depended upon the thickness of the Cr layer. When Cr thickness was reduced to 135 Å, both Au-rich and GaAs-rich excessive compound formation started to occur. The Au diffusion punched through the InGaAs layer and penetrated into the InP. Comparison of Au/Zn/Au and Au/Zn/Au/Cr/Au suggested that the top Au layer maybe very influential during the alloy reaction. The Au–Zn alloy was significantly less in the Au/Zn/Au than that in the Au/Zn/Au/Cr/Au.

Fatigue Properties of Cast Ag-Pd-Cu-Au-Zn Alloy for Dental Applications in the Relation with Casting Defects

Ag–Pd–Cu–Au–Zn type alloys have been widely used as dental prosthetic materials. In general, the dental prosthetic products are fabricated by a dental casting method. The dental castings contain the casting defects such as micro shrinkages, pores, surface roughness, etc. Cyclic stress, that is, fatigue stress due to the mastification is applied to the dental prosthesis in the practical use. Therefore, the effects of the casting defects such as micro shrinkages, pores and surface roughness on the fatigue properties of the cast Ag–Pd–Cu–Au–Zn type alloy were investigated in the comparison with the fatigue properties of the drawn Ag–Pd–Cu–Au–Zn alloy in this study. Fatigue tests of Ag–Pd–Cu–Au–Zn alloy cast using a dental casting machine were carried out, and then the fatigue properties of the cast alloy were investigated in the relation with casting defects. The fatigue strength of the cast Ag–Pd–Cu–Au–Zn alloy is considerably smaller than that of the drawn Ag–Pd–Cu–Au–Zn alloy. The fatigue crack of the cast alloy initiates preferentially at the shrinkage near the specimen surface. The scatter of the fatigue strength of the cast alloy becomes to be small by relating the fatigue life with the maximum stress intensity factor calculated assuming the shrinkage that becomes to be a fatigue crack initiation site as a initial crack. This means that the size of the shrinkage affects the fatigue strength of this cast alloy strongly. The tolerant size of the shrinkage that satisfies the target value of the fatigue limit (230 MPa) of this cast alloy is calculated to be below 80 \\micron using the equation derived in this study, which describes the relationship between the maximum stress intensity factor and the number of the cycles to failure.

Effect of deposition parameters on the electrical and metallurgical properties of Au-Zn contacts to p-type InP

The electrical and metallurgical properties of Au-Zn contacts to p-type InP, prepared by vacuum evaporation of Au-Zn (10 wt%) alloy, were investigated as a function of deposition parameters and annealing conditions. The deposition rate of Au-Zn alloy was found to be the major factor that strongly influences the properties of as-deposited and annealed p-InP/Au-Zn contacts. At a substrate temperature of about 150 degrees C, when a high deposition rate of about 16-25 nm s-1 was used, excellent homogeneous ohmic contacts could be formed after annealing with specific contact resistance values of about 1*10-8 Omega m2 (for NA-ND=(0.8-1.0)*1024m-3). In contrast, a low deposition rate of about 0.1 nm s-1 resulted in a large scattering of resistance values and non-ohmic behaviour of contacts. In this case, a much smaller amount of zinc and its non-uniform distribution in the Au-Zn layer, as well as strong InP/Au-Zn interfacial reactions, were detected by AES and SEM techniques. The electrical and metallurgical properties of slow-deposited Au-Zn contacts could be improved by use of a lower substrate temperature (in the range of 30-50 degrees C) during contact deposition.

Technological aspects of the preparation of Au-Zn ohmic contacts to p-type InP

Au-Zn/Au and X/Au-Zn/Y/Au metallizations (where X=Au, Cr or Ni is a nucleation layer and Y=Cr or Ni is a diffusion barrier), formed by vacuum evaporation of Au-Zn (10 wt%) alloy, were studied for the preparation of ohmic contacts to p-type InP. The metallurgical and electrical properties of such contacts were investigated as a function of deposition parameters (especially the deposition rate of Au-Zn alloy) and alloying conditions. The role of the nucleation layer X on the InP surface and of the barrier layer Y between the Au-Zn and the outer Au layer in contact formation is also discussed.

Ohmic contacts on p-type Ga 0.47In 0.53As/InP

Ohmic contacts of Au and Ag based Zn containing alloys on p-type Ga 0.47In 0.53As have been studied using intermediate layers of Ti and Ni, respectively. Low specific contact resistance in the order of 10 −5 Ωcm 2 are achieved. In case of AuZn alloy, the Ti intermediate metal layer causes higher contact resistances together with a worse contact morphology in contrast to Ni intermediate layers. However for AgZn contacts Ti adherent layers improve the contact resistances, especially for lower alloying temperatures. Moreover these contacts exhibit significant smoother interfaces as revealed by TEM micrographs. Thus AgZn contacts apply best to low resistive contacting of very thin p-layers forming e.g. the base of a ballistic device.

X-Ray Measurement of Order in the Beta-Prime Phases of Noble Metal Alloys. I. β'AuZn

The long range order parameter of the β'AuZn alloy of the L 2 0 -type structure has been measured by X-ray diffraction at temperatures ranging from 200°C to 650°C, the latter temperature being 75°C below the melting point T m . Relative intensities of several h 00 type reflections from single crystals have been measured using a counter diffractometer equipped with a high temperature attachment. It has been observed that the order parameter gradually decreases with rising temperature but appears to keep an appreciably high value at T m . An abnormal increase in the lattice spacing has also been observed at about 550°C, which corresponds to the onset of an appreciable disordering detected by the intensity measurement. It is concluded that β'AuZn is a special type of ordered alloy and it would undergo a transition into the disordered alloy state, if it were not melted. The root-mean-square displacement of atoms due to thermal vibration has been measured as a function of temperature. At room temperature the d...

Study on the Ordered Phases with Long Period in the Gold-Zinc Alloy System II. Structure Analysis of Au3Zn[R1], Au3Zn[R2] and Au3+Zn

Crystal structures of the ordered phases, Au 3 Zn[R 1 ], Au 3 Zn[R 2 ] and Au 3+ Zn are investigated by X-ray diffraction using single crystals. The structure models proposed by Wilkens and Schubert for Au 3 Zn[R 1 ] and Au 3+ Zn are confirmed substantially, but partly corrected. The structure analysis of a new phase Au 3 Zn[R 1 ] is given, and the stacking faults present in this phase is investigated. It is suggested that the complicated atom shifts similar to those in Au 3 Zn[R 1 ] and Au 3 Zn[R 2 ] take place also in Au 3+ Zn. It is proposed that such complicated atom shifts seem to be a phenomenon not peculiar to the ordered phases in the Au-Zn alloy system but common to the ordered phases with long periods, such as Au 3 Cd, Ag 3 Mg, Cu 3 Pd, CuAu II.

Study on the Ordered Phases with Long Period in the Gold-Zinc Alloy System I. Survey of Crystal Structures and Calorimetric Measurement

The crystal structures of the ordered phases in the Au-Zn alloy system have been studied in detail by means of X-ray and electron diffraction on single crystal samples, and the order-disorder and other kinds of phase transitions involved in the present system have also been studied by the measurement of specific heat. The previously proposed structures of Au 3+ Zn, Au 3 Zn[H], Au 3 Zn[R] have substantially been confirmed and that of Au 5 Zn 3 only partly. Moreover, the details in these structures have been revealed: in Au 3+ Zn some type of the strong lattice modulation is present, and in Au 3 Zn[R] the two types of structure. Au 3 Zn[R 1 ] and Au 3 Zn[R 2 ], certainly exist. The transition behavior of the alloys with changing temperature has been investigated on samples of various compositions and the thermodynamic data obtained are presented. The phase diagram of the Au-rich side of the present system is reasonably corrected by the present experiment. The orientation distribution of the ordered crystals...