Dependence of the sizes of damaged regions around indium contacts to p-type CdHgTe on GaAs substrates on the annealing temperature and time

It is found that damaged regions are formed around indium contacts to p-type CdHgTe {310} heteroepitaxail layers (HELs) on GaAs substrates and the sizes of these regions depend on the temperature and time of annealing in air. It is shown experimentally that at an annealing temperature of 90 °C, the rate of expansion of the damaged regions is about 4 µm/h, and at temperatures of 120 °C, it is more than 25 µm/h. After 488 hours of annealing of plates of CdHgTe HELs at 60 °C in air, the formation of damaged regions around the indium contacts to the p regions was not observed. The studies were performed on plates of p-type CdHgTe HELs on GaAs substrates whose surface was covered with SiO₂ and Si₃N₄ dielectrics (with a total thickness of about 0.15 µm), with windows where p-n junctions were generated by ion implantation of boron.     

Processing of hollow micro- and nanostructures using the hydrophilic nature of MgO

We show that covering the water-saturated MgO surface with an Al₂O₃ film using atomic layer deposition and then annealing it at 400 °C leads to plastic deformation of alumina by trapped water vapor with consequent development of hollow structures. This phenomenon is applied to thin films, nanopatterned surfaces and isolated 3D nanostructures.     

VO2/GaAs异质结的制备及其光电特性研究

采用直流磁控溅射和后退火氧化工艺在p型GaAs单晶衬底上成功制备了n-VO_2/pGaAs异质结,研究了不同退火温度和退火时间对VO_2/GaAs异质结性能的影响,并分析其结晶取向、化学组分、膜层质量以及光电特性。结果表明,在退火时间2 h和退火温度693 K下能得到相变性能最佳的VO_2薄膜,相变前后电阻变化约2个数量级。VO_2/GaAs异质结在308 K、318 K和328 K温度下具有较好的整流特性,对应温度下的阈值跳变电压分别为6.9 V、6.6 V和6.2 V,该结果为基于VO_2相变特性的异质结光电器件的设计与应用提供了可行性。     

New mechanism for field-induced anisotropy of cobalt-rich amorphous alloys

It is generally assumed that amorphous magnetic alloys respond to field annealing by a process of local directional ordering which leaves the amorphous structure intact. We have made a comparative microstructural study of field-annealed Co_95-xFe₅(BSi)x amorphous alloys using transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) with thin sections parallel to the ribbon surface. Field annealing response was measured from anisotropy in low-field hysteresis loops. These alloys show appreciable surface crystallization for annealing as much as 80 K below the bulk crystallization temperature. The surface crystallization proceeds by a known mechanism (selective oxidation) to which we have added a more detailed understanding. Three steps are involved: (1) formation of an amorphous borosilicate surface oxide layer during annealing; (2) depletion of glass stabilizing elements (boron and silicon) from the underlying amorphous metal substrate; (3) primary crystallization of the destabilized, metal-enriched subsurface layer to an fee or hep cobalt-rich phase. Striking differences in the microstructural morphology were revealed for different glass former ratios B/Si. For high B/Si ratios, the surface crystallites are predominantly fee Co and show a high density of oxygen faults. For low B/Si ratios, the surface crystallites are predominantly hep Co and almost free of faults. Response to field annealing is proportional to the B/Si ratio and correlates with the presence of oxygen faults in surface crystallites. Electron diffraction and microprobe analysis indicate that the surface oxide in silicon-rich alloys is a dense silica glass which appears to be an effective diffusion barrier to oxygen. The surface oxide in boron-rich alloys is a more porous oxide richer in B₂O₃. These observations appear to be related to those from perminvar alloys where oxygen was found to be necessary for field annealing to be effective.     

Annealing treatment of amorphous silicon generated by single point diamond turning

Mechanical material removal during ultraprecision machining of semiconductor crystals normally induces surface damage. In this article, Raman micro-spectroscopy has been used to probe structural alteration as well as residual stresses in the machined surface generated by single point diamond turning. The damage found is characterized by an amorphous phase in the outmost surface layer. In addition, the results of in-situ re-crystallization annealing of micromachined silicon monitored by micro-Raman spectroscopy are reported for the first time. It is also shown that the annealing heat treatment influenced surface roughness, whereby R_max was equal to 24.3 nm and 47.5 nm for the non-treated and annealed surfaces, respectively.     

Time evolution of sigma 3 annealing twins in secondary recrystallized nickel

Samples of commercially pure nickel have been annealed in air at 0.68T_m (900 °C) for 1, 2 and 3 h in order to study the relationship between the grain growth characteristics and grain boundary misorientation, particularly annealing twins (Σ 3). Orientation mapping by electron backscatter diffraction was used to obtain the experimental data. Anomalous grain growth was observed in commercially pure nickel after each of the anneals. The main findings are as follows. The texture was mainly {100}<001> and {112}<111> and it was more pronounced in coarse-grained areas than in fine-grained areas. The length fraction of Σ 3s (annealing twins) increased with annealing time and therefore with the level of anomalous grain growth. Two to three twins per grain were sited in coarse-grained regions whereas less than one twin per grain was sited in fine-grained regions. It is suggested that the nucleation and growth of twinning is mechanistically linked to anomalous grain growth.     

Surface finish of bulk metallic glass using sequential abrasive jet polishing and annealing processes

Surface finish plays an important role in product quality due to its direct effects on product appearance. Hence, improvement of the surface finish is an essential requirement in industrial products. In an attempt to improve the surface finish of bulk metallic glass (BMG) material, several common methods have been used, such as milling, grinding, and lapping. However, the BMG surface finish has not yet been significantly improved by using these methods. Therefore, this paper proposes sequential abrasive jet polishing (AJP) and annealing processes that can considerably improve the BMG surface finish. In addition, this paper also takes into account optimal parameters for the AJP and annealing processes based on the Taguchi’s L ₁₈ and L ₈ orthogonal array experimental results, respectively. The experimental results show that using optimal AJP parameters, the surface roughness (R _a) of the ground specimens can be significantly improved from 0.675 to 0.016 μm. After the AJP process, the surface roughness (R _a) of the polished specimens can be further improved from 5.7 to 2 nm within an area of 5?×?5 μm by using optimal annealing parameters.     

Synthesis and microstructural studies of annealed Cu2O/CuxS bilayer as transparent electrode material for photovoltaic and energy storage devices

Cu₂O thin film and a transparent bilayer have been fabricated by electrodeposition method. The growths were obtained in potentiostatic mode with gradual degradation of anodic current. X‐ray diffraction (XRD) study showed that the bilayer is polycrystalline and it possesses mixture of different crystallite phases of copper oxides. Surface morphology of the films was investigated by scanning electron microscopy (SEM). The SEM images revealed that the films were uniformly distributed and the starting material (Cu₂O) had cubical structure. Grains agglomeration and crystallinity were enhanced by annealing. Optical studies indicated that all the samples have direct allowed transition. Energy band gap of the bilayer film was reduced by annealing treatment thus corroborating quantum confinement upshot.     

Investigations of microstructures and defect structures in wear affected region created on Nimonic 80A during high temperature wear

The microstructures of a wear induced surface glazed layers formed during sliding wear of Nimonic 80A against Stellite 6 at 20–750 °C using a speed of 0.314 m s^-1 under a load of 7 N have been investigated using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) in combination with energy dispersive X-ray (EDX) analysis. The defects formed in the glazed layers were measured by positron lifetime spectroscopy. The results indicate the formation of a wear resistant nanostructured glazed layer. Positron lifetime and Doppler-broadening measurements demonstrated that the defects (mainly dislocations) existed in the glazed layers at low temperatures which increasing wear test temperature led to decrease in defects density. Positron measurements also suggested that, at the annealing temperature (1200 °C), the presence of dislocations might lead to the formation of ordered or partially ordered regions in Nimonic 80A.     

The formation of micro-blisters on Al–Mg alloy surfaces during hot rolling

Micro-blisters occurring on the surfaces of Al–Mg alloys after the first hot rolling pass were studied. The micro-blisters had a nanocrystyalline structure and comprised of an outer MgO shell and an inner Al/Al₂O₃ lining. It is proposed that the micro-blisters are linked to the presence of carbide particles protruding from the work roll surface and the evolution of hydrogen from the reaction of water vapor, permeated through the porous oxide-rich surface layer, with the bulk aluminum.     

The optimization of annealing and cold-drawing in the manufacture of the Ni�CTi shape memory alloy ultra-thin wire

In this paper, the mechanical properties of the Ni?C50.5?at.%?CTi alloy super-elastic wires manufactured by a conditioned multi-passed process of annealing and cold-drawing have been studied. The annealing temperature of 450~800°C, time of 20?min~3?h and the cold-drawing amount of 6.9%~39% were chosen. Their effects on the thermo, mechanical, and surface morphology of the Ni?CTi wires have been studied. The differential scanning calorimetry and tensile-recovery tests were adopted to obtain the phase transformation temperatures and mechanical hysteresis of the Ni?CTi SMA wires with different treatment conditions. The results show that the phase transition temperature of Ni?CTi wire can be changed by varying the annealing temperature and time; cold-drawing deformation and subsequent annealing have a great influence on the super-elasticity. The process with 39% cold-drawing amount, 600°C and 20?min annealing is shown to be effective in the manufacturing.     

Transition of the lubricated wear of carbon steel

To study the transition of the lubricated wear of 0.53% C steel in the steady state, wear tests were carried out by rubbing the annular surfaces of two cylindrical test pieces in machine oil with no additives. The ratio of mating areas was varied to approach actual contact conditions. Three regions of variation in the coefficient of friction with contact load were determined. Fatigue wear, characterized by a friction coefficient μ ≈ 0.05 and a specific wear rate ω_s ≈ 0.005 × 10^?6 mm³ N^?1 m^?1, occurs in the first region.A transition from fatigue wear to adhesive wear, with μ ≈ 0.05?0.12 and ω_s ≈ (0.005?0.05) × 10^?6 mm³ N^?1 m^?1, takes place gradually within a specific load range. Finally, adhesive wear predominates above the load level that marks the end of the transition. The same behaviour was analysed through stepwise loading tests. The onset of transition and seizure occurs at constant mean surface temperatures. However, the end of transition is also affected by factors other than temperature. The results are compared with the transitions reported by the International Research Group on Wear of Engineering Materials of the Organization for Economic Cooperation and Development.     

Tribofilm formation and mild wear by tribo-sintering of nanometer-sized oxide particles on rubbing steel surfaces

The present study is the first to show that the supply of nanometer-sized particles of Fe₂O₃, SnO₂, CuO, or Bi₂O₃ oxide on rubbing steel surfaces induces transition to mild wear with sliding distance, and that the wear transition behavior depends on the type of supplied oxide. The mild wear is due to formation of the wear-protective tribofilm on the rubbing surfaces, and observations confirm that the tribofilms are produced by tribo-sintering of the supplied oxide particles. The mild wear transition behavior is explained by the sintering rate of the supplied oxide particles, which is related to the oxygen diffusion coefficient in the oxide and the particle diameter. When the supplied oxide is of high diffusivity, the tribofilm formation rate is high, owing to the high sintering rate of the oxide particles, and the mild wear transition occurs at a short sliding distance. In the case of Fe₂O₃ oxide, the sliding distance of the transition from severe to mild wear is decreased when finer particles are supplied, suggesting that fine particles are easily sintered on the wear surface.     

A study on the annealing characteristics of BAF for cold rolled steel strip

The cold spot temperature control system for BAF (Batch Annealing Furnace) has been established in order to reduce energy consumption to improve productivity and to stabilize the properties of products. We improved material quality, increased output, and decreased the annealing cost and homogeneous distribution of cold spot temperature in BAF. The introduction of H₂ instead of N₂ as atmospheric gas, combined with high convection in BAF, has resulted in a considerable increase in furnace efficiency and material quality. By the low density, high diffusibility, and reducing character of H₂, a better heat transfer resulting in uniform material temperature and improved coil surface can be achieved. The results in this study are as follows: Heating time is reduced to one half by increasing the inflow rate of atmospheric gas and changing of atmospheric gas component from HN_x(H₂: 5 %, N₂: 95%) to Ax(₂: 75%, N₂: 25%) gas. The annealing cycle time is also reduced to 2.7 times. In the case of HNx BAF the cold spot moved to the center after 32 hours of heating, while in the case of H₂ BAF it moved from the one-third position of the B coli inside to the center juster after 12 hours of heating, resulting from a heat transfer increase to the radius direction. The temperature in this part is higher than any other parts when cooling. Soaking time at batch annealing cycle is decided by input coil width, and the time for quality homogenization of 1219 mm width coil must be longer by 2.0 hours than that of 914 mm width coil with the same coil weight at H₂ BAF, however, it is necessary to make 2.5 hours longer at HNx BAF.     

A novel method for the fabrication of AlGaN/GaN HEMTs on Si (111) substrates

In this paper, the development of a novel manufacturing process is presented for fabricating high-quality AlGaN/GaN high-electron-mobility transistors (HEMTs) on Si (111) substrates. Various material and processing approaches regarding surface passivation, gate oxide, ohmic contact metal, and post-gate annealing are evaluated in terms of device performance. In order to achieve better immunity to current collapse effects, we conducted experiments that investigate the relationship between the AlGaN/GaN HEMTs’ electrical characteristics and different passivation films by plasma-enhanced chemical vapour deposition. In order to obtain a better ohmic contact performance, we tested a Ti/Al/Ta/Au ohmic contact metallisation scheme using different annealing temperatures and annealing times to achieve a lower contact resistance, a more proper line edge definition, and a better surface morphology. A post-gate N₂ rapid thermal annealing method done after the gate metallisation process has shown better DC current–voltage output, transfer characteristics, and gate–drain breakdown voltage results compared to the as-fabricated HEMTs. A HEMT with a 0.5-μm gate length, exhibiting a maximum drain current density of 750 mA/mm, a peak transconductance of 220 mS/mm, a unity-gain cut-off frequency of 24.6 GHz, and a maximum frequency of oscillation of 45.4 GHz, was fabricated using this novel manufacturing process; the X-band power performances demonstrate a 5.8-W/mm output power density and a 51 % power-added efficiency.     

The Third International Conference on Scanning Tunnelling Electron Microscopy

The transition quasi-crystalline→crystalline is found to be very sluggish in the ternary alloy Al₆₀Mn₁₁Ni₄. This makes it possible to study in detail the relationship between the decagonal phase, obtained after furnace cooling, and two different crystalline phases, which result after long annealing at 400°C. Use is made of electron diffraction, high resolution electron microscopy and optical diffraction. The crystalline phases still exhibit features which are closely related to those of the decagonal phase. This can be concluded from a comparison of the electron diffraction patterns of the quasi-crystalline phase along a number of zones, with those of the crystalline phases along corresponding zones. The crystalline phases contain different types of defects which are analysed in detail using high resolution images and diffuse scattering in the electron diffraction patterns. The close relationship between the electron diffraction patterns of the crystalline and quasi-crystalline phases is explained in terms of general optical principles. Some characteristic features of a model of the quasi-crystalline phase are tentatively proposed.     

电火花沉积电极材料过渡机制及规律

利用旋转电极电火花沉积装置,在Q235钢表面逐层沉积1至6层铜合金涂层,计算分析了每层沉积厚度、过渡形态、表面和截面形貌,探讨了电火花沉积电极材料的过渡机制、形态和规律。结果表明：工件和电极的质量变化曲线相似,随着沉积层数的增加,质量变化量减少直至趋于稳定;沉积层以熔融物质团（液态、半固态）的形态过渡沉积生成,电极与工件材料在沉积层与基体界面处互相渗透,生成厚约20~30 μm的过渡层;工件材料对沉积层的稀释作用主要发生在过渡物质团结合处,对其内部影响极小,且随着沉积层数的增加而减小,沉积层由多层电极材料覆盖叠压构成;随着沉积层数的增大,放电能量利用率降低,单次沉积厚度降低,电极对沉积表面的磨削涂覆作用增大,电极材料沉积率有所下降。     

The crack healing behavior of ZrO2/SiC composite ceramics with TiO2 additive

This paper was carried out to assess the crack-healing behavior of ZrO₂ composite ceramics. The ZrO₂ composite ceramics were made by adding 10 wt.% SiC and TiO₂. The TiO₂ additives were changed to 1, 3 and 5 wt.%. The characteristics of crack-healing behavior were studied as a function of annealing temperature and time. Specimens were mirror polished. The cracks of about 100 ??m were introduced on the specimen surface by Vickers indenter and specimen were heat-treated. The strength of crack-healing was conducted by a three-point bending, and the each specimens was measured by XRD. The results obtained in this study are as follows: The ZST composite ceramics contained crack-healing properties, and the strength of ZST smooth specimens have been shown to be better than ZS specimens. The optimum crack-healing condition of the ZTS3 specimen was 1073 K, 5 hours in the air. Specimens with heat treatment had micro-cracks and large cracks on the surface, but the micro-cracks on the surface did not affect the bending strength. It was found that specimens display phase transformation from tetragonal crystal to monoclinic crystal after heat treatment.     

退火对牺牲层腐蚀前端形状和腐蚀速率的影响

从片子的生长工艺出发对腐蚀前端的形状进行了研究。提出了应力是产生腐蚀前端三角形的主要原因的推测，并通过退火实验验证了这一推测。在对退火处理影响腐蚀速率机制研究的基础上，得出了不同退火条件对腐蚀速率的影响规律。     

Surface Damage Characteristics of Self-Assembled Monolayers of Alkanethiols on Metal Surfaces

The effect of metal oxide layer on the nano-tribological characteristics of single chain alkanethiol (CH₃(CH₂) _n SH) self-assembled monolayers (SAMs) on various metal surfaces (gold, silver, copper) was investigated. In order to correlate the surface structures with the tribological characteristics, various surface analysis techniques such as Scanning Probe Microscopy, X-ray Photoelectron Spectroscopy, Secondary Ion Mass Spectrometry and Spectroscopic Ellipsometry were used. Results of surface analyses showed that thiols on a metal surface were susceptible to forming multilayers if the metal surface was oxidized before the thiol assembly process. From the friction and wear tests conducted using an Atomic Force Microscope and a Lateral Force Microscope, it was found that thiols on copper oxide surface could be easily removed even under a few nano-Newton normal load. On the other hand, thiols on gold and copper fresh surfaces (the surface which was made by minimizing oxide formation) could endure up to micro-Newton level loads. Based on these findings, it could be concluded that the nano-tribological characteristics of alkanethiol SAMs on various metal surfaces were largely dependent on the oxide layer that already formed on the metal surface before the thiol adsorption process.