Bottom Of Grooves Research Articles

Preparation and photoluminescence study of patterned substrate quantum wires

GaAs/AlGaAs quantum wires grown by molecular beam epitaxy on a V-groove patterned substrate was described. The cross section of scan electron microscopy (SEM) image shows that crescent-type quantum wire were formed at the V groove bottom, which is a triangle of about 60nm in width and 14nm in height. Two peaks at 793.7nm and 799.5nm of photoluminescence spectrum at 87K verified the existence of quantum wires. Theoretical calculation gives 8meV blue shift, which is proved to be casued by lateral confinement compared with quantum well of the same width.

Picosecond Laser Patterning of ITO Thin Films

We present a comparative study of picosecond laser patterning of ITO thin films for OLED applications using 355nm, 532nm and 1064nm radiation. Front side and rear side patterning was investigated and single pulse ablation thresholds were determined for all three wavelengths and both irradiation sides. Good ablation quality was achieved by using 1064nm front side irradiation resulting in a smooth groove bottom, almost vanishing ridges at the groove rims and a neglectable heat affected zone.

Strength enhancement of autocompleting medium and high carbon steels friction welded joints

An autocompleting friction welding method, which was developed by the authors, is to weld with using a rotating insert piece set between fixed workpieces. The conditions to enhance the strength of the welded joint in an autocompleting friction welding method which involves a rotating insert between the fixed workpieces were determined. The weld faying surface of the fixed specimen had a 10 mm diameter. When MCS joint was made at an insert thickness of 4 mm through a friction pressure of 36 MPa, it did not achieve 100% joint efficiency because the weld interfaces were not completely joined. MCS joint had 100% joint efficiency and fractured on the MCS base metal although the crack was generated at the weld interface, when that was made at an inner groove diameter of 11 mm with the bottom of the grooves for the insert piece (groove bottom thickness) of 0.9 mm or more through a friction pressure of 90 MPa. To obtain a joint with no cracks, MCS joint was made with an inner groove diameter of 12 mm at a friction pressure of 90 MPa. When the groove bottom thickness was 0.75 mm, MCS joint had 100% joint efficiency and the MCS base metal fracture with no crack at the weld interface. When HCS joint was made with an inner groove diameter of 11 mm at friction pressures of 90 and 150 MPa, it did not achieve 100% joint efficiency because the weld interfaces were not joined completely. The weld interfaces of HCS joint at a friction pressure of 120 MPa were completely joined although it did not achieve 100% joint efficiency. To improve the joint efficiency, HCS joint was made with an insert thickness of 5 mm, a groove bottom thickness of 0.64 mm, and an inner groove diameter of 12 mm with a friction pressure of 120 MPa. HCS joint had 100% joint efficiency and fractured on the HCS base metal with no crack at the weld interface.

Simulation of the surface profile of the groove bottom enveloped by milling cutters in single screw compressors

In machining of a single screw compressor, the milling technique of screw rotor grooves with cylindrical milling cutters has far higher machining efficiency than turning. But, the screw groove bottom surface produced by the flat end of milling cutters will fail to mesh with the flat tooth tip hermetically, and thus give rise to compressed gas leakage. This paper carries out a mathematic simulation of the screw groove bottom surface profiles. The research brings screw groove bottom profiles machined by different cylindrical milling cutters to light, and provides some references for designing the column envelope meshing pairs in single screw compressors.

Consolidation of Hydrophobic Transition Criteria by Using an Approximate Energy Minimization Approach

Recent experimental work has successfully revealed pressure induced transition from Cassie to Wenzel state on rough hydrophobic substrates. Formulas, based on geometric considerations and imposed pressure, have been developed as transition criteria. In the past, transition has also been considered as a process of overcoming the energy barrier between the Cassie and Wenzel states. A unified understanding of the various considerations of transition has not been apparent. To address this issue, in this work, we consolidate the transition criteria with a homogenized energy minimization approach. This approach decouples the problem of minimizing the energy to wet the rough substrate, from the energy of the macroscopic drop. It is seen that the transition from Cassie to Wenzel state, due to depinning of the liquid-air interface, emerges from the approximate energy minimization approach if the pressure-volume energy associated with the impaled liquid in the roughness is included. This transition can be viewed as a process in which the work done by the pressure force is greater than the barrier due to the surface energy associated with wetting the roughness. It is argued that another transition mechanism, due to a sagging liquid-air interface that touches the bottom of the roughness grooves, is not typically relevant if the substrate roughness is designed such that the Cassie state is at lower energy compared to the Wenzel state.

接合自己完了型摩擦圧接した高張力鋼継手の特性とその改善

This paper describes the joint properties and its improvement of high tensile strength steel joint by an autocompleting friction welding method, that method was developed by authors. The base metal was 800MPa class high tensile strength steel. The weld faying surface of the fixed specimen had a 10mm diameter, and the effect of the thickness and that at the bottom of the grooves (groove bottom thickness) for the insert piece on the joining phenomena and joint properties were investigated. The value of a circumferential shear fracture (CSF value) was defined and calculated by the ratio between the theoretical and the actual generated friction torques. When the CSF value was lower than 1, the insert piece had the circumferential shear fracture before the friction torque reached the initial peak. Also, when the CSF value was larger than 1, the insert piece had the circumferential shear fracture after the friction torque reached the initial peak. When the joint was made at the insert thickness of 5mm with the CSF value of nearly 1, that had 100% joint efficiency although it had the softened region at the near of the weld interfaces. The joint had cracks at the weld interface when it was made with friction pressures of 36 and 120MPa. However, the joint had no crack at the weld interface when it was made with a friction pressure of 90MPa. When the joint was made at the insert thickness of 4mm with the CSF value of nearly 1, that had also 100% joint efficiency although it had the softened region at the near of the weld interfaces. However, the softened region at the weld interface of the joint with the insert thickness of 4mm was lower than that with 5mm. Also, this joint had 90 degrees bend ductility with no crack at the weld interface. In conclusion, a joint with no cracks for high tensile strength steel was able to make by an autocompleting friction welding method.

Shape transitions and island nucleation for Si/Ge molecular beam epitaxy on stripe-patterned Si (001) substrate

Si and Ge growth on the stripe patterned Si (001) substrates is studied using scanning tunneling microscopy. During Si buffer growth, the stripe morphology rapidly evolves from multifaceted ''U'' to ''V''-shaped forms. This involves successive transitions between different low energy (11n) side facets, where n continuously decreases from n=3 to 20. Ge growth on such stripes induces the formation of a pronounced side wall ripple structure when the Ge thickness exceeds three monolayers. This ripple structure consists of alternating (105) microfacets oriented perpendicularly to the stripes. Depending of the side wall geometry, Ge nanoislands subsequently nucleate either on the side walls or at the bottom of grooves. The latter only occurs for ''V''-shaped stripes, where the side wall ripples extend all the way from the top to the bottom of the grooves, allowing efficient downward mass transport. For multifaceted ''U'' stripes, the side wall ripples are interrupted by steeper side wall segments such that mounds and subsequently, pyramids and domes grow on the side walls instead of at the bottom of the grooves. The island shapes strongly depend on their position on the pattern topography, which also affects the critical coverage for island nucleation as well as for the transitionmore » from pyramids to domes. The mechanisms for nucleation at different positions are clarified by detailed analysis and the role of kinetic as well as energetic factors identified.« less

Selection guide of insert piece shape for steel joint by autocompleting friction welding method

An autocompleting friction welding method, which was developed by the authors, is to weld with using a rotating insert piece set between fixed base metals. This paper describes the selection guide of the insert piece size for steel joints by the autocompleting friction welding method. The base metal was low carbon steel (LCS), and the weld faying surface of the fixed specimen had a 10 mm diameter. The effect of the thickness at the bottom of the grooves for the insert piece (groove bottom thickness) on the joining phenomena was investigated. When the joint was made at a friction pressure of 90 MPa with a friction speed of 27·5 s−1, the insert piece had a shear fracture towards the circumferential direction (circumferential shear fracture) in the peripheral portion of the weld interfaces by the initial peak produced during the friction process. In this case, the insert piece had the following dimensions: the thickness was 4·0 mm, and the groove bottom thickness was 1·2 mm or over with an inner groove diameter of 11 mm. In particular, the joint with a groove bottom thickness of 1·2 mm had 100% joint efficiency and the LCS base metal fracture with no crack at the weld interface. The value of a circumferential shear fracture (CSF value) was defined and calculated by the ratio between the theoretical and the actual generated friction torques. When the CSF value nearly equalled 1, the joint had 100% joint efficiency and the LCS base metal fracture with no crack at the weld interface.

Geometric Design Investigation of Single Screw Compressor Rotor Grooves Produced by Cylindrical Milling

Cylindrical milling of a screw rotor groove in a single screw compressor has higher machining efficiency than turning. However, the screw groove bottom produced by the flat end of the milling cutter fails to mesh hermetically with the flat tooth tip due to the oversized clearance between them. The clearance forms two leakage paths leading to a compressed gas leakage. The shape of the path is roughly the same as that of two parallel oblate divergent nozzles in an inverse orientation. A mathematical simulation is presented for the surface profile of the screw groove bottom for a single screw compressor generated using several cylindrical milling cutters. The results contribute to improving the design of the meshing pairs in the single screw compressor.

Growth of m ‐GaN layers by epitaxial lateral overgrowth from sapphire sidewalls

AbstractNonpolar m ‐plane GaN layers were fabricated by epitaxial lateral overgrowth from etched sapphire sidewalls. The m ‐plane GaN layers with c ‐direction growth were grown from patterned c ‐plane and a ‐plane sapphire substrates with a ‐plane or c ‐plane sidewalls using a low‐temperature buffer layer. The growth of GaN from the surface was prevented by a SiO2 mask, and that from the bottom of grooves was also prevented by deep grooves. Thus, the growth orientation relative to the surface of the GaN layer was determined by the growth of the GaN layer from the sapphire sidewalls. Consequently, m ‐plane GaN layers were grown on c ‐plane sapphire with a ‐plane sidewalls or on a ‐plane sapphire with c ‐plane sidewalls with the terrace regions covered with a SiO2 mask and deep grooves. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Effect of tilt angle on cutting regime transition in glass micromilling

Recent development in mechanical micromachining technology has increased the realization of micromachining as a feasible manufacturing process of micro-scale components including glass-based devices. It has been found that glass can be machined in a ductile regime under certain controlled cutting configurations. However, favorable ductile regime machining instead of brittle regime machining in micromilling of brittle glass is still not fully understood as a function of cutting configuration. In this study, the effect of tilt angle along the feed direction on cutting regime transition has been studied in micromilling crown glass with a micro-ball end mill. Straight glass grooves were machined in water bath by varying the tool tilt angle and the feed rate, and the resulting surface was characterized using the scanning electron microscope and the profilometer to investigate the glass cutting regime transition. In characterizing the cutting regimes in glass micromilling, rubbing, ductile machining, and brittle machining regimes are hypothesized according to the undeformed chip thickness. It is found that a crack-free glass surface can be better machined in the ductile mode using a 45° tilt angle and feed rates up to 0.32 mm/min. During each milling pass, surface roughness was found to decrease from the entry zone to the groove bottom and then increase to the exit zone regardless of the cutting regime.

Fabrication of SiC particle reinforced composite on aluminium surface by friction stir processing

A feasibility investigation has been carried out of the formation of surface composite by uniformly distributing SiC particles 1˙25 µm in size into a surface layer of an A 1050-H24 Al plate through friction stir processing (FSP). The SiC particle was filled into a groove cut on the Al plate, covered by an Al sheet 2 mm thick, and a rotating tool was penetrated from the cover sheet so that the probe tip reached a depth beyond the groove bottom. The effects of process parameters (rotation speed and travelling speed) and applying multiple passes on the distribution of SiC particle in the nugget zone were investigated. The effects of groove size and its position relative to the tool probe were also investigated. Applying multiple passes had a great effect on the homogeneity of the SiC particle distribution. At rotation speeds of 2000–3000 rev min−1, the SiC particles tended to cluster in some places in the nugget zone. By decreasing the rotation speed to 1000–1500 rev min−1, the SiC particle was distributed in almost all the nugget zone area when the groove was 2–3 mm wide and 1˙5 mm deep. On the other hand, the stirring action of FSP was insufficient to distribute homogenously the SiC particles when the groove size was increased to 3×2 mm. By shifting the groove position towards the advancing side of the tool probe, the distribution of the SiC particles in the nugget zone became better. The defect free nugget zone with homogenously distributed SiC particles was obtained in a sample produced by FSP at rotation speeds of 1500 rev min−1 for the first pass and 1250 rev min−1 for the second and third passes. Microhardness of the nugget zone was increased to a level as high as 55 HV when the groove size was 3×1˙5 mm. The effect of the rotation speed on the particles dispersion was discussed with particular reference to the vertical material flow in the nugget zone.

Investigation of Nanoscratch Processes in Semiconductor Materials for Application to Maskless Patterning

Features of nanoscratching processes with a diamond 90 degrees cube corner tip in semiconductor materials have been studied with different tip orientations and scratch procedures: constant and linearly increasing normal load during scratching, multi-scratching and the direct analysis of the generated scratch by re-scanning the scratch with a strongly reduced normal load. These scratch functions allowed a detailed investigation of the materials response due to the mechanical deformation process. Elastic material recovery, plastic deformation and material removal contribute to the generation of scratch groove profiles. For low applied normal loads mainly elastic deformation occurs whereas for larger normal loads stick-slip processes with periodic hillocks at the groove bottom and irregular pile-up along the scratch rim dominate the process. From the analysis of the scratch groove profile in Si(100), GaAs(100) and thin InSb films, quantitative values for the elastic deformation, the friction coefficient, stick-slip pattern, material removal and scratch depth as a function of the applied normal load are obtained. With multi-scratching a definite removal pattern with a reproducible scratch depth is obtained. These results can be used to optimise the scratch technique for application to maskless patterning.

In situ endpoint detection of reactive ion-beam etching of dielectric gratings with an etch-stop layer using downstream mass spectrometry

Downstream mass spectrometry is successfully used in the reactive ion-beam etching of dielectric diffraction gratings of deep grooves with vertical sidewalls to achieve in situ endpoint detection. Silica (SiO 2) gratings with a Sc 2O 3 etch-stop layer are fabricated by reactive ion-beam etching with CHF 3 as etchant, and the mass spectrometric signal of SiF 3 + produced by the reactive etching of the SiO 2 grating material is monitored. When the etch-stop layer is reached, a drop of this signal occurs. By comparing the monitoring curves and resulting gratings of different etching methods, we find that the decrease of the monitored signal is strongly influenced by the sidewall steepness of the etched grating grooves. All conditions being equal, the greater sidewall steepness renders the faster decrease of the signal. Consequently, the proposed approach of endpoint detection applies well to the gratings with steep sidewalls. With the help of two previously developed methods, the sidewall steepness of grating grooves is increased, and the optimal endpoint is detected. Employing the proposed technique, we have reproducibly fabricated dielectric gratings with proper groove depth and even groove bottom.

Fluids mixing in devices with connected-groove channels

A novel connected-groove micromixer (CGM) has been designed, fabricated, and investigated thoroughly. Connected grooves in this device, crossing multiple sides of the microchannel induced an intensely transverse field of fluids, and thus generating rapid mixing than patterned grooves on a single side alone. The fabrication of a CGM was facilitated to overcome the complication of fabricating the sidewall and bottom grooves in a channel simultaneously; a CGM hence became highly efficient and compact. We propose here CGM of two types—CGM-1 and CGM-2—and compare their mixing performance with a slanted-groove micromixer (SGM) numerically and experimentally for Re over a wide range (1–100). Numerical analysis demonstrated that a CGM provided intense transverse components in the field and great mixing efficiency; in particular, CGM-2 with co-rotating flows encompassing the mechanisms of cutting and blending of fluids had a mixing performance over 50% better than an SGM for Re = 1 – 100 . To systematically analyze the mixing by experiments, mixing of slightly viscous fluids, highly viscous fluids, and bio-fluids were adopted, respectively. The mixing experiments of slightly viscous dye solutions on the basis of the color uniformity of mixture showed that mixing lengths of both CGM were smaller than that of SGM. Based on the mixing results of highly viscous fluids, CGM-1 with sidewall grooves had a shorter pitch of spiral flow and more helical turns than an SGM. With a confocal microscope we explored the mixing sections of fluorescent proteins (B-phycoerythrin, BPE; Allophycocyanin alpha subunit, ApcA) inside a micromixer to confirm the numerical results.

Development of autocompleting friction welding method

This paper describes an autocompleting friction welding method that was carried out to weld with an insert piece set between fixed base metals. The base metal was low carbon steel, and the faying surface of the fixed specimen had a 10 mm diameter. The effect of the thickness of the insert piece (insert thickness) on the joining phenomena was investigated. When the insert thickness was 3˙2 mm and the friction welding conditions were a friction speed of 27˙5 s–1 and friction pressure of 36 MPa, the insert piece had a shear fracture toward the circumferential direction in the peripheral portion of the weld interfaces by the initial peak produced during the friction process. The joint also had cracks at the adjacent region of the weld interfaces, although it had the same tensile strength as the base metal. On the other hand, the joint made using the insert piece with a groove on its peripheral portion had the same tensile strength as the base metal, where it fractured. This joint also had 90° bend ductility without cracks. In this case, the optimum insert thickness was 4˙0 mm, and the thickness at the bottom of the grooves (groove bottom thickness) was 1˙2 mm with an 11 mm inner groove diameter, and the friction welding conditions were a friction speed of 27˙5 s–1 and friction pressure of 36 MPa. In conclusion, a sound friction welded joint was made by an autocompleting friction welding method.

Aspect-ratio-independent anisotropic silicon etching in a plasma chemical cyclic process

The conditions of implementation of aspect-ratio-independent etching (ARIE) are given for a two-stage etching/passivation process in an SF6/C4F8 plasma. It is shown experimentally that the ARIE etching is achieved by extension of the stage of passivation and/or reduction of the energy of ions at the stage of etching. These phenomena lead to prolonged removal of the fluorocarbon film, which affects the dependence of the etching rate on the aspect ratio of the groove. A model of cyclic etching is presented that takes into account the aspect dependences of the processes on the groove bottom, namely, Si etching and deposition and removal of the fluorocarbon film. The simulation results correlate satisfactorily with the experimental data. Limitations of implementation of ARIE etching are discussed.

Channelling surface plasmons

Channel plasmon polaritons (CPPs) propagating along the bottom of subwavelength grooves cut into a metal surface were recently shown to exhibit strong confinement combined with low propagation loss, a feature that makes this guiding configuration very promising for the realisation of ultracompact photonic components. Here, the results of our investigations of CPP guiding by V-grooves cut into gold are presented, demonstrating efficient large-angle bending and splitting of radiation as well as waveguide-ring resonators and Bragg grating filters. Additionally, we present a simple model based on the effective-index method that accounts for the main features of CPP guiding, thus, providing a clear physical picture of this phenomenon.

Analysis on folding defects of inner grooved copper tubes during ball spin forming

This paper mainly focuses on the folding which is the main defect on the inner surface of the inner grooved copper tube during ball spin forming. The material model and two-dimensional geometrical model of finite element simulation of multi-step ball spinning for forming inner grooved copper tubes have been built. The folding defects formed both on one side of the fin and on the bottom of inner grooves of the copper tubes had been analyzed according to the finite element results such as strain distribution, metal flow and contact state between the copper tube and the plug. Efficient measures have been proposed to prevent the folding defects. The SEM observation on the inner surface of the finished inner grooved copper tubes has been performed to illustrate the folding distribution and shape. Metallographic observation on the microstructure of cross-section of the copper tubes has been performed to analyze the forming process of folding. The results of the finite element simulation agree well with the experimental observation of the folding defects on the inner surface and the microstructure of cross-section of the inner grooved copper tubes.

21510 cBNブレードを用いたマイクロ溝加工に関する研究(微細加工,OS.13 微細加工)

various studies on groove machining of single-crystal silicon have been done because it is used extensively as semiconductor devices. Micro groove machining is expected as the application for reaction promotion of chemical catalyst to increase material surface area to form micro grooves in material surface. Therefore, groove microfabrication technology of high hardness steel is strongly expected to establish. This machining method is also expected to apply as the new die machining. In this report, the micro groove machining of steel material using cBN blade is realized with accurate groove profile that depth is 100μm. The burr height, karf width and microasperity of groove bottom are evaluated under the various machining conditions.