Showing papers on "Annealing (metallurgy) published in 1974"

The annealing of dislocations in high-angle grain boundaries

Abstract: Hot-stage electron microscopy is used to study the annealing behaviour of lattice dislocations in high-angle grain boundaries in Ni, Ni 5% Al, austenitic stainless steel and Al 0·9 % Mg. The observations indicate that individual dislocations are incorporated in a boundary by a spreading of their cores or a dissociation into partial dislocations with small Burgers vectors. This process results in a rearrangement of the grain boundary structure by grain boundary diffusion. It is shown that this process enables a random grain boundary to incorporate more than 1012 dislocations cm−2 at the recrystallization temperature.

Introduction rates and annealing of defects in ion‐implanted SiO2 layers on Si

Abstract: The introduction rates and isochronal annealing behavior of structural defects created by atomic collision or ionization in SiO2 layers thermally grown on Si in O2 and steam are investigated by measuring the induced volume compaction for ion and electron bombardments. The use of compaction measurements permits study of the introduction and annealing of defects with little confusion from changes in the charge state of the defects. The structural damage created by ion energy deposited into atomic collisions is found to be complex, possibly consistent with a thermal process involving reordering of the noncrystalline network of Si–O tetrahedra, and to anneal in a slow featureless manner beginning around 300°C and returning to the original density near the original growth temperature. The structural damage created by ion or electron energy deposited into ionization is identified with broken Si‐O bonds and found to anneal completely in a single well‐defined stage centered at 650°C. The ionization‐induced structural defect is the same for ion and electron ionization if no appreciable atomic collision energy deposition occurs simultaneously. Additional structural damage arising from an interaction between atomic collisions and ionization is demonstrated. The results demonstrate that other workers' observation of annealing in damaged oxides at 300°C corresponds to emptying of charged defects rather than annealing of the structural defects.

Preparation and properties of high‐Tc Nb–Ge films

Abstract: Using a previously reported low‐energy sputtering technique, Nb‐Ge films have been prepared with superconducting Tc's up to ∼23 K. High‐field, x‐ray, and annealing results are reported for these highest‐Tc films. A discussion of the critical parameters required to achieve the highest transition temperatures in the Nb–Ge system is given. Also further arguments in support of the theories that these highest Tc's are due to the formation of the stoichiometric Nb3Ge phase in the sputtered films are presented.

Radiation-induced diffusion of point-defects during low-temperature electron irradiation

Abstract: Electron irradiation damage in lead was studied in a high-voltage electron microscope at temperatures between 8 and 300 K. The formation and growth of interstitial clusters was observed during irradiation at temperatures between 8 and 165 K and of vacancy clusters between 50 and 165 K, i.e. at temperatures well below annealing stage III (at ∼170K in lead). The observation of vacancy cluster growth is interpreted as evidence for preferential absorption of interstitials at sample surfaces. By a combination of above-and sub-threshold irradiations and in situ annealing treatments it could be shown that the point-defect motion responsible for cluster formation below Stage III is of radiation-induced nature. The importance of radiation-induced diffusion for the low-temperature irradiation and the annealing behaviour of lead and gold is discussed. Various mechanisms which may be responsible for radiation-induced defect migration and its main characteristics are considered.

Effects on interface barrier energies of metal‐aluminum oxide‐semiconductor (MAS) structures as a function of metal electrode material, charge trapping, and annealing

Abstract: Energy barrier heights at the interfaces of metal‐aluminum oxide‐silicon structures have been measured via internal photoemission as a function of metal electrode material, premetallization annealing treatment, and charge trapping. Barrier heights at the Si–Al2O3 interface were insensitive to gate metal, annealing treatment, and charge trapping. Zero‐field energy barriers for the Au, Ni, Al, or Mg and Al2O3 interfaces were found to be 4.1±0.1, 3.7±0.1, 3.2±0.1, and 2.5±0.1 eV, respectively. Effects of charge trapping on the barrier height were measurable only for the Mg–Al2O3 interface. Annealing treatments had no effects on barrier heights within the accuracy of the measurement technique.

Role of sequential annealing, oxidation, and diffusion upon defect generation in ion‐implanted silicon surfaces

Abstract: Ion implantation of boron was substituted for the chemical deposition of boron in the manufacture of a bipolar integrated circuit. The n+p+ test diodes were found to exhibit excessive reverse leakage while the p+n test diodes behaved normally. This was attributed to the defect structures developed by the interaction of sequential diffusion with defect nuclei introduced by ion implantation. We have found that the low‐temperature annealing treatments which are used to return full electrical activity to the implanted atoms leave a high density of defect nuclei in the implanted area. When the silicon surface is subjected to wet oxidation, these defect nuclei expand to form stacking faults or dislocations loops of such size that they can be detected by chemical etching and optical microscopy. This technique has permitted us to determine the annealing temperatures necessary to eliminate these implantation‐induced defect nuclei. A model is presented to describe the manner in which defect nuclei are generated by ...

Annealing properties of ion‐implanted p‐n junctions in silicon

Abstract: Phosphorus‐, arsenic‐, and boron‐implanted junctions have been investigated with special emphasis on their annealing behavior of the junction‐leakage currents. It is shown that a minimum of about 900°C and 30 min annealing is required for junction qualities equal to that of diffused ones. Hall‐effect measurements of the implanted region show that about 900°C for phosphorus annealing and 1000°C for arsenic and boron annealing are required to restore carrier concentrations corresponding to the implanted impurities, respectively. The relative importance of surface area and perimeter contribution to the junction leakage is identified. It is shown that for an area‐to‐perimeter ratio smaller than about 1 mil, the perimeter contribution dominates. There are indications that the distribution of the leakage contributing g‐r centers coincide with the implanted impurities.

Structure of electroplated and vapor‐deposited copper films. III. Recrystallization and grain growth

Abstract: Changes in the structure of electroplated and vapor‐deposited copper thin films, as a result of isothermal and isochronal annealing in the temperature range 100–500 °C, have been investigated by x‐ray diffraction and metallographic techniques. In the electroplated films, recrystallization occurred with an activation energy of about 0.65 eV until the recrystallized grains attained sizes comparable to the film thickness. In vapor‐deposited films, such recrystallization is believed to take place immediately after deposition on heated substrates. Grain growth in both sets of copper films proceeded with an activation energy of about 1.55 eV, until a limiting grain size was reached. This limiting grain size is shown to be dependent on the film thickness and the extent of texture present.

Determination of deep trap levels in silicon using ion-implantation and CV-measurements

Abstract: Differential capacitance measurements on Schottky barrier contacts are used to determinedeep energy levels for 29 different impurities implanted into silicon. Back-ground doping and deep levels are separated by making use of the sharply peaked implantation distribution. Donor or acceptor behavior is identified by the shape of the measured apparent charge profile. Energy levels measured for many impurities after annealing of the radiation damage agree with values known from literature. Other levels are caused by a non-thermal state of incorporation into the silicon lattice, e.g. for C, Si, and Ge, even after annealing of the radiation damage. Some impurities, e.g. Nb, Ni, Ti, and Na, show more than one state of incorporation, concentrations of which vary with the annealing conditions. Many implanted elements, especially those having a low solubility, e.g. Au, Be, Co, Se, etc., show strong out-diffusion and precipitation at the surface at annealing temperatures around 500°C.

The high-temperature hardness of various phases in steel

Abstract: Apparatus constructed in the Department of Metallurgy and Materials Science, University of Cambridge, has enabled the hot hardness of the individual steel phases, ferrite, austenite, cementite, pearlite, Type I MnS, Mn–MnS eutectic, and silicates to be measured in situ with a high degree of accuracy. The work was undertaken in the context of studies of the deformation behaviour of non-metallic inclusions in steel, where the relative yield behaviour of inclusions and matrix is clearly a significant factor. Because of their wider interest the hot hardness results are presented separately. The high-temperature hardness of pearlite, of significance in its behaviour in ‘warm’ working, has been explained in terms of the hardness of its constituent phases.

The synthesis of Nb 3 Ge by RF sputtering

Abstract: The conditions necessary for the formation of Nb 3 Ge by low-pressure rf sputtering with a superconducting transition temperatureT c >21 K have been investigated. Samples have been deposited onto cooled substrates so that the film is first amorphous and then is crystallized by a subsequent annealing, and onto hot substrates, in which case the film is crystalline upon deposition. The highestT c samples were obtained for a substrate temperature of 735±25° C. The optimum substrate temperature is the same as the optimum annealing temperature for crystallizing films which were first deposited onto cooled substrates. Special conditions are necessary for the formation of single-phase A15 samples of Nb 3 Ge with an optimumT c . We have utilized the collisions that the sputtered atoms undergo with the sputtering gas molecules to thermalize the sputtered atoms. We report here on sputtering in both krypton and in argon.

Annealing studies of solution and bulk crystallized polyethylene using the Raman-active longitudinal acoustical vibrational mode

Abstract: The longitudinal acoustical (LA) mode has been studied in solution and bulk-crystallized polyethylene by Raman spectroscopy. In bulk-crystallized polyethylene the crystalline repeat, estimated from the LA frequency, corresponds to the larger of the two small angle repeat distances. Observations of the LA linewidth indicate that upon annealing the distribution of lamellar thicknesses broadens for single crystal mats and narrows for quenched bulk material. In successive annealing experiments on preannealed polyethylene where the spectra were recorded at the annealing temperature, the crystalline core maintains a constant thickness and does not melt-inward from the fold surfaces. The intensity of the LA mode decreases during such annealing. These results are interpreted in terms of the α-relaxation process which increases the number of defect chains in the crystalline core upon annealing.

Columnar grains and twins in high-purity sputter-deposited copper

Abstract: Columnar grains were normal to the substrate in thick, high-purity copper deposits made by high-rate (80–110 A/sec) sputter deposition. The grains contained a high density of stacking faults and twin boundaries parallel to the substrate. The columnar grains for a deposit made at 6 °C, 80 A/sec, and with a −75 V substrate to anode bias were uniformly about 700 A in diameter, but a deposit made at 100 °C, 110 A/sec, and with a −20 V bias had a few large grains with diameters up to 13 000 A and many smaller grains with diameters of about 2500 A. Deposits made at 100 °C did not recrystallize, but deposits made at −196 °C and at about 10 °C recrystallized at room temperature. Recrystallized regions had annealing twins that were 1000–10 000 A across. The deposits had (111) crystallographic planes parallel to the substrate before recrystallization, but after recrystallization (100) planes were parallel to the substrate. Chemical analyses for impurity elements in the sputtering target material and a deposit showed four elements not detected in the target material were detectable in the deposit. Krypton gas pickup in the deposits during sputtering was estimated to be less than 5 ppm.

Correlation of magnetic and mechanical properties with microstructure in Fe/Co/2-3 pct V alloys

Abstract: Remendur is an alloy of approximately equal proportions of iron and cobalt with two to four wt pct vanadium. In previous articles by the authors, various aspects of the ternary phase equilibrium and the influence of processing variations on microstructure were described. This paper reports on the more complete correlation among microstructure, mechanical properties, magnetic properties, and resistivity. For strand annealed (900 to 950°C) material, the mechanical properties are only a weak function of annealing temperature but a strong function of vanadium content. Subsequent annealing at 600°C significantly increases the yield and tensile strengths but the mode of fracture becomes brittle cleavage, in contrast to the ductile failure of strand annealed material. Coercivity in the strand annealed (900 to 950°C) and quenched condition is primarily determined by grain size and transformation strains produced during the quench. Coercivity in 600°C annealed material is due to the fine dispersion of stable γ particles in the α′1 matrix which are impediments to domain wall motion. In general, resistivity is relatively independent of processing temperature.

Influence of heat treatments on microstructures in an Fe--Co--V alloy

Abstract: The microstructural changes in an Fe-Co-V alloy (composition by wt pct: 2.97 V, 48.70 Co, 47.34 Fe and balance impurities, such as C, P and Ni) resulting from different heat treatments have been evaluated by optical metallography and transmission electron microscopy. Results indicate that, on air cooling or quenching into iced-brine from the high temperature single-phase γ (fcc) field, vanadium can be retained in a supersaturated solid solution (α2) which has bcc structure. For the range of cooling rates employed, a portion of the material appears to undergo the γ-α2 transformation massively and the remainder martensitically. Also antiphase boundaries are observed in the air-cooled samples. On annealing in the two-phase α1 + γ field, α2 decomposes into vanadium-rich subgrains (γ) and vanadium-poor subgrains (γ1), and only the former undergo the γ → α2 transformation during air cooling or iced-brine quenching. The α1t subgrains in a sample, slowly quenched in quartz, show superlattice dislocations and antiphase boundaries, whereas both the transformed and untransformed areas exhibit (100) superlattice reflections. There is, however, no evidence of long-range order in the specimens quenched into iced-brine. The two-phase annealing sequence followed by a 2 h anneal at 600°C and air cooling results in precipitation within the vanadium-rich, transformed subgrains. Also there is evidence of long-range order in both types of subgrains.

The application of the loop annealing technique to self diffusion studies in silicon

Abstract: The loop annealing technique has been applied to the study of self diffusion in silicon over a wide range of doping concentrations. The results show that the diffusion coefficient decreases as the concentration of n-type dopant decreases and the concentration of p-type dopant increases. At a fixed temperature, the diffusion coefficient is linearly dependent on the electron concentration and this behaviour is in accord with the point defects responsible for self diffusion behaving as acceptors. The values obtained for the self diffusion coefficient in intrinsic material are in good agreement with those obtained by other workers at higher temperatures using profiling techniques and indicate a slight curvature in the Arrhenius plot.