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Search for amorphous materials with high crystallization temperature and investigation of crystal orientation, surface morphology, and composition distribution of MgO/bcc-Cr80Mn20/amorphous-Co60W40 underlayer were conducted. As a result, the crystallization temperature of amorphous-Co60W40 is higher than 620 °C and it proved to be suitable as texture inducing layer material. Also, it was found that a network-shaped upheaval structure corresponding to the grain size of the (002) plane oriented CrMn grains was formed on the surface of the (002) plane oriented MgO layer. By utilizing the surface roughness of the underlayer, we proposed a columnar isolated granular medium for heat-assisted magnetic recording (HAMR) by using the FePt-oxide granular layer/pure FePt islandlike initial nucleus layer/networklike upheaval underlayer.

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) provide an opportunity to investigate diverse scientific phenomena at an atomic level and have effective technological potential. In recent times, unlike conventional TMDCs, platinum diselenide (PtSe2) has garnered considerable attention owing to its i) fascinating electrical and optical features coupled with mechanical strain and ii) scalable synthesis method. However, its local electrical/tribological/mechanical properties are yet to be examined in detail. In this study, we prepared two different types of PtSe2 layers by controlling the thickness of the Pt-seed film: i) one with horizontal alignments, which are made from ultrathin Pt films and ii) one with vertical and horizontal alignments, which are made from a relatively thick Pt film. Then, the local tribological, mechanical, and electrical properties of PtSe2 were evaluated mainly with scanning probe microscopy (SPM). The local friction study unveiled the marked friction variation depending on the layer directions. An additional study on the local mechanical property indicated that the apparent modulus difference between the two growth directions can lead to dissimilar friction behaviors. Furthermore, local current probing using SPM showed that PtSe2 with both layer directions provides ohmic features to both directions, although the magnitude of conductance along the horizontal direction is ~100 times smaller than that along the vertical one. On the contrary, PtSe2 with only in-plane alignments is configured with multiple horizontal PtSe2 layers, densely stitching themselves together one after another with a very narrow trench region at their boundary. Surprisingly, a local current–voltage spectroscopy analysis showed a small current gap on the bridged trench region, in contrast to the ohmic behavior of the grain interior. This indicates that the local metal-to-semiconductor transition is available, owing to thin PtSe2 layers in the trench regions. The following study at macroscale showed how the overall electrical and thermoelectric properties of PtSe2 can be influenced by local structures triggered by the variation in Pt-seed thickness. The results not only provide a new insight on better understanding the intrinsic features of 2D PtSe2, but also offer important characterization guidance on tailoring their functionalities.

Cr 100-x Ti x amorphous texture-inducing layers (TIL) were investigated to realize highly (002) oriented L1₀ FePt-C granular films through hetero-epitaxial growth on the (002) textured bcc-Cr 80 Mn 20 seed layer (bcc-SL). Asdeposited TILs showed the amorphous phase in Ti content of 30 ≤ x (at%) ≤ 75. Particularly, films with 40 ≤ x ≤ 60 kept the amorphous phase against the heat treatment over 600 ℃. It was found that preference of the crystallographic texture for bcc-SLs is directly affected by the structural phase of TILs. (002) crystallographic texture was realized in bcc-SLs deposited on the amorphous TILs (40 ≤ x ≤ 70), whereas (110) texture was formed in bcc-SLs overlying on crystalline TILs (x ＜ 30 and x ＞ 70). Correlation between the angular distribution of (002) crystal orientation of bcc-SL evaluated by full width at half maximum of (002) diffraction (FWHM) and a grain diameter of bcc-SL indicated that while the development of the lateral growth for bcc-SL grain reduces FWHM, crystallization of amorphous TILs hinders FWHM. L1₀ FePt-C granular films were fabricated under the substrate heating process over 600 ℃ with having different FWHM of bcc-SL. Hysteresis loops showed that squareness (M r /M s ) of the films increased from 0.87 to 0.95 when FWHM of bcc-SL decreased from 13.7 ˚ to 3.8 ˚. It is suggested that the reduction of (002) FWHM affects to the overlying MgO film as well as FePt-C granular film by means of the hetero-epitaxial growth.

This paper reports the results of a study on the microstructure evolution of sputtered BiSb–Te thermoelectric films during post-annealing and its effects on their electronic transport and thermoelectric properties. Combining X-ray diffraction, transmission electron microscopy, and Raman spectroscopy, we illuminate the fundamental aspects of the microstructure evolution: the as-deposited film was Bi0.5Sb1.5Te3 compound in the Bi2Te3-type phase with a nano-crystalline microstructure and the post-annealing prompted a drastic grain growth. The electrical and thermoelectric properties also closely changed following the trend of the grain growth. The Seebeck coefficient, electron mobility, and thermal conductivity increase while the carrier concentration remains flat. The ZT value escalates systematically with the annealing time increasing, reaching around 0.94 after 12 h annealing.

Thermoelectric power waves, where multiwalled carbon nanotubes coated with cyclotrimethylene trinitramine (MWCNT/TNA) directly convert chemical energy to electricity, have received considerable attention recently. However, the low Seebeck coefficient of carbon nanotubes has been regarded as a hurdle to increasing the electrical potential. Here, we present Sb2Te3-coated MWCNT arrays prepared by a sputtering method. An analytical model predicts an increase in Seebeck coefficient of the annular multishell structure by ∼75%. The heterostructure coupled with exothermic chemical reaction of TNA demonstrates an increase in peak electrical potential of 175% (∼198 mV), compared with typical outputs of bare MWCNT/TNA (∼72 mV). A serial connection of two repeating units increased the peak potential by up to 406 mV.

In recent years, heat-assisted magnetic recording is being actively studied for trilemma breaker in the hope that higher temperatures will assist magnetic reversal of small grain with high.

This paper investigates the effects of the Sb content (х) on (Bi1−xSbx–2Te3 thermoelectric films with х changing widely from 0 (Sb2Te3) to 1 (Bi2 Te3). First, the XRD analysis discloses that with the Sb content (x) increasing, the phase changed gradually from Bi2Te3 to Sb2Te3 as Sb atoms replaced substitutionally Bi atoms. Further microstructure analysis reveals that an extensive grain growth occurred during post-annealing for the samples with high Sb contents. According to the measurement of electrical and thermoelectric properties, the polarity of the charge carrier and Seebeck coefficient switched n-type to p-type in the range of x = 0.45∼0.63. For the n-type samples, the power factor is highest when x = 0.18 around 46.01 μW/K2 whereas Sb2Te3, for the p-type samples, shows the highest value, 62.48 μW/K2cm.

We have evaluated the effect of wet chemical treatment on the interfacial bonding strength of Cu-to-Cu direct bonding. The oxide on a Cu-deposited wafer can be removed by a solution made of hydrofluoric acid and sulfuric acid (HF/H2SO4) or diluted hydrochloric acid (HCl/H2O), which can also improve the bonding quality of Cu-to-Cu bonds. Two 4-inch Cu-deposited wafers were bonded at 250 degrees C via the thermo-compression method. The interfacial adhesion energy of Cu-to-Cu bonding was quantitatively measured by the four-point bending method. After chemical pretreatment for 30 seconds with HF/H2SO4 and HCl:H2O solutions, the measured interfacial adhesion energies were 4.91 J/m2 and 5.51 J/m2, respectively. Microstructural examination of the Cu bonding interfaces showed that the interfacial bonding quality of Cu-to-Cu bonds improved under proper wet chemical etching conditions. Wafer-level cleaning by wet chemical treatment of the Cu surface was found to be a very effective way to improve the bonding quality of Cu bonds, even at bonding temperatures lower than 300 degrees C.

This study provides a framework for evaluating the drop reliability of solder joints using a high-speed lap-shear test. The test specimens employed here were Sn-37Pb/Cu under bump metallization (UBM) solder joints and were aged for 120h at different temperatures (120, 150, and 170^[email protected]?) to examine the effects of aging. We tested them at different loading speeds in the range of 0.01-500mm/s. A careful analysis of the stress-strain graphs attained from the tests, coupled with characterization of the fracture surfaces, discloses that the fracture mode shifts from ductile to brittle as the loading speed escalates. A map of the fracture mode shows that how readily the mode transition with the loading speed occurs can be directly translated into the drop reliability of the solder joint, disclosing that the drop reliability would deteriorate as the aging temperature increases possibly due to the increased IMC thickness. These results underscore the utility of the experimental methodology adopted in this study to evaluate the drop reliability of solder joints.

This study examined the thermal stability of an electroless-plated Ni(P) barrier layer inserted between Sn and Cu in the bonding structure of Cu/Sn/Cu for three-dimensional (3D) interconnect applications. A combination of transmission electron microscopy (TEM) and scanning electron microscopy allowed us to fully characterize the bonding morphology of the Cu/Ni(P)/Sn/Ni(P)/Cu joints bonded at various temperatures. The barrier suppressed Cu and Sn interdiffusion very effectively up to 300°C; however, an interfacial reaction between Ni(P) and Sn led to gradual decomposition into Ni3P and Ni3Sn4. Upon 350°C bonding, the interfacial reaction brought about complete disintegration of the barrier in local areas, which allowed unhindered interdiffusion between Cu and Sn.

This study examined the sensitive effects of composition on the microstructure evolution and thermoelectric properties of sputtered Bi-Te films. Bi-Te films of various Te compositions (49 at.% to 60 at.%) were grown by cosputtering deposition and annealed at 200°C for different durations. We examined the microstructure of the films using x-ray diffraction (XRD) and transmission electron microscopy (TEM), and measured the electronic transport and thermoelectric properties. As the Te composition of the films changed from 49 at.% to 60 at.%, the phase of the as-sputtered film changed from the rhombohedral BiTe-type phase to the metastable rock-salt phase, which eventually transformed to the Bi2Te3-type phase upon annealing, instigating microstructure evolution. This phase transformation profoundly influenced the electrical and thermoelectric properties of the films.

This paper reports the microstructure evolution of Bi-Te thermoelectric films upon post-annealing and its effects on the thermoelectric properties. Bi-Te films with the composition of around 61at.% Te and the thickness of 300nm were deposited onto SiO"2-coated Si substrates by using bismuth and tellurium targets in a radio frequency (RF) magnetron sputtering system. We annealed the films at different temperatures (100, 150 and 200^oC) under N"2 ambient for 8h, and characterized the crystallinity and morphology of the Bi-Te films. Microstructure characterization using X-ray diffraction and scanning electron microscopy disclosed that the post-annealing treatment entailed a drastic microstructural evolution by inducing the development of a strong texture of grains with their c-axis oriented normal to the substrate. In addition, we measured the electrical transport and thermoelectric properties of the films to reveal their close link with the microstructure changes. The electron mobility and Seebeck coefficient increase significantly, leading to a remarkable improvement in the power factor from [email protected]/K^2cm for the as-deposited sample to [email protected]/K^2cm for the 200^oC-annealed sample.

Due to the high occurrence rate of musculoskeletal disorders(MSDs), many Korean companies adopted various assessment tools to evaluate workers' musculoskeletal stress. Using the results of this evaluation, tasks were selected for improvements. However, there are still many workers who complained of musculoskeletal stress of their tasks. Their tasks usually consist of repetitive activities and a short rest cycle. This prompts a concern of reliability of the evaluation tools and especially RULA. Thus in this study, OCRA(The Occupational Repetitive Action tool) was used to check whether RULA(Rapid Upper Limb Assessment) evaluates workers' musculoskeletal stress reasonably well since OCRA has been known to be a good evaluation tool for repetitive tasks and tasks with short recovery periods. The evaluation was conducted on 142 tasks. It was found that 65 tasks showed higher action levels by OCRA than by RULA. However, 13 tasks showed the reversed result and 64 tasks showed the same level regardless of the evaluation tool. It was concluded that either RULA or OCRA alone cannot evaluate all types of tasks very well. It is suggested that OCRA needs to be used with RULA together for the evaluations of musculoskeletal stress at workplaces where repetitive activities and short recovery periods exist.

In this study, we explore various electrode materials (Au, Ti, and Sb) for use as contact materials on Bi2Te3 and Sb2Te3 thermoelectric films. Using the transmission line method (TLM), we measured the specific resistivity of the contacts, which showed that Au has the lowest contact resistivity for both the thermoelectric films (after annealing): 2.7 × 10−10 Ω m2 for Bi2Te3 and 2.9 × 10−11 Ω m2 for Sb2Te3. The specific contact resistivity data suggest that the dominant factor for the contact properties is interface states. After annealing, the contact resistivity does not change much for the Bi2Te3 contacts while it drops greatly for the Sb2Te3 ones. Analysis of the carrier transport mechanism across the contacts discloses that changes in the carrier concentration in the thermoelectric films after annealing are responsible for the different behaviors.

The purpose of this study was to evaluate the outcomes of arthroscopy-guided direct suprascapular nerve block performed after arthroscopic rotator cuff repair. In the present prospective, randomized, double-blinded clinical study, 30 patients were divided into two groups: 15 patients (group I) were treated with arthroscopy-guided suprascapular nerve block using 10 mL 0.5 % ropivacaine with 1:200,000 epinephrine, and 15 patients (group II) were treated with placebo using 10 mL 0.9 % saline after arthroscopic rotator cuff repair. Patient pain levels were measured using the visual analog scale (VAS) at 1, 3, 6, 12, 18, and 24 h post-operatively. Additionally, the number of boluses and total amount of fentanyl dispensed by patient-controlled analgesia administration during the 24-h post-operative period were evaluated. VAS scores did not differ significantly between groups I and II during the 24-h post-operative period, but mean fentanyl bolus consumption was significantly less in group I compared with group II (p = 0.015). Arthroscopy-guided suprascapular nerve block at the end of a rotator cuff repair was safe and less time-consuming than expected. Although this procedure did not significantly reduce the post-operative pain, the post-operative need for fentanyl boluses as analgesia was reduced significantly, and it would be beneficial if this procedure involved a sensory branch of axillary nerve block or was performed at the beginning of the arthroscopic procedure. Prospective, randomized, double-blinded clinical trial, Level I.

This study utilized out high speed lap-shear tests at various strain rates (0.01 mm/s ~ 500 mm/s) for Sn-37Pb/Cu and Sn-37Pb/ENIG solder joints to evaluate the drop reliability. The samples aged for 120 h at different temperatures (150°C and 170°C) were also tested to examine the effects of aging on the drop reliability. We thoroughly analyzed the stress-strain curves obtained from the lap-shear tests and the fractured surfaces. This analysis generated insightful information that reveals three fracture surface types active in our samples. This study also elucidates different fracture mode for the Sn-37Pb/Cu and Sn-37Pb/ENIG solder joints. This study successfully demonstrates that the analysis based on a high speed lap-shear test could be critically used to evaluate the drop reliability of solder joints.

Effect of bcc Cr80Mn20 seed layer and Cr50Ti50 amorphous texture inducing layer on the heteroepitaxy system in FePt-C granular film was studied by introducing a new concept of the layered structure. The concept suggested that the large grain seed layer in which the crystallographic texture was initially formed on an amorphous layer in the layered structure can reduce the angular distribution of (002) c-axis crystal orientation in the FePt-C granular film owing to heteroepitaxial growth. Structure analysis by X-ray diffraction revealed that (1) when the substrate heating temperature was elevated from 300 °C to 500 °C, grain size in the seed layer increased from 9.8 nm to 11.6 nm, and then decreased with further increasing the substrate temperature. The reduction of the grain size over 500 °C corresponds to the crystallization of the amorphous texture inducing layer, (2) when the grain size increased from 9.8 nm to 11.6 nm, the angular distribution of the (002) orientation in the seed layer dramatically dec...

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The decoupling and enhancement of both Seebeck coefficient and electrical conductivity were achieved by constructing the c-axis preferentially oriented nanoscale Sb(2)Te(3) film on monolayer graphene. The external graphene layer provided a highway for charge carriers, which were stored in the thicker binary telluride film, due to the extremely high mobility.