ALBERT

Notes: We report a GaAs passivation method using sulfidation and hydrogenation to achieve the Au/GaAs interface free of defective interfacial compounds, through which improves the electrical properties of the Schottky contact. A sulfur-passivated GaAs Schottky diode exhibited improved contact properties, for example an enhanced barrier height and the lower reverse leakage current compared to the diode with conventional HCl-cleaned GaAs. The combination of the H-plasma treatment and the predeposition of an ultrathin Au overlayer enable to control the defective interfacial state of metallization-induced excess As: the Au overlayer seems to effectively protect GaAs from plasma-induced damage and attenuate the energy of penetrating hydrogen then the hydrogenated interface became defect-free since interfacial excess As effectively sublimated as volatile As hydrides. The reverse leakage current was reduced by an order and photoluminescence efficiency was greatly enhanced while there was no change in the dopant profile of GaAs substrate and none of Si–H. We describe a mechanism of the evolution of interfacial bonds during the processes to correlate to the improved electrical properties, which are systematically characterized by the surface/interface analysis tools such as x-ray photoelectron spectroscopy and attenuated-total-reflection Fourier-transform infrared spectroscopy and particularly the role of excess As is discussed in detail. © 2001 American Institute of Physics.

Notes: A two-step passivation using sulfidation and hydrogenation has been reported to improve the gate leakage current and breakdown voltage of the GaAs metal–semiconductor field-effect transistor (MESFET). The combination of S passivation and interfacial hydrogenation was applied to the gate line in the MESFET; leakage current was reduced over an order and breakdown voltage was improved to a maximum level of 14 V from 10 V. It was revealed that the improvement of device properties after this two-step treatment resulted from the suppression of defective states such as oxides and excess As at the interface of the gate junction. The evolution of their bonding states through the treatment was found to have a close relationship with the device parameters. © 2002 American Institute of Physics.

Notes: The uniform and dense structure of thin films is influenced by the texture of films. It was good to have uniform and dense structure and bad to have an open columnar structure in TiN thin films. Therefore, the property of diffusion barrier of the TiN films in semiconductor also is related to the texture and microstructure of TiN coated layers. In this study, the relationships between the textures and microstructures and the properties of TiN films on semiconductor were investigated under different processing methods (PVD and MOCVD). The property of diffusion barrier of RFsputtered (PVD) TiN is better than that of metal organic chemical vapor deposited (MOCVD) TiN thin films. Also the property of diffusion barrier of PVD (111) textured TiN is better than that of PVD (100) textured TiN thin films on oxidized Si wafer

Notes: Electrodeposited Ni films were produced by using four types of electrodeposition methods, direct current without additive (DC), direct current with additive (AD), square pulse without additive (SP) and square pulse with additive (AS). The 〈100〉 texture was obtained by using the DC method at about 20 °C and by using the AD and the AS methods at about 80°C. The 〈110〉 texture was obtained by using the DC and the SP methods at about 80 °C. When using the AS method, the surface roughness of Ni deposit was lower than that of Ni deposits after using the other electrodepositon methods and the microstructure of Ni deposits showed nanocrystalline grain size. The 〈100〉 textures of Ni deposits using the DC and the AS methods remained unchanged after the recrystallization process. The 〈110〉 texture of Ni deposits using the SP method at about 80 °C changed to 〈 3 1 0〉orientation after the recrystallization process

Notes: . Equal channel angular pressing (ECAP) is useful method to obtain the ultra-fine grained and the high hardened metal. The microstructure, the hardness, and the texture of the 1050 Al sheets by ECAP are changed by a severe shear deformation. The change of the microstructure, the hardness, and the texture were investigated on the 1050 Al sheets that were prepared by ECAP and annealing

Notes: TiN coated films were prepared by a reactive ion physical vapor deposition method. In this research, we studied the relationships between textures and friction coefficient, erosion-corrosion resistance and corrosion resistance in textured TiN films. The surface roughness of (115) textured TiN films is lower than that of (111) textured TiN films. The friction coefficient of (115) textured surface is similar with that of (111) textured surface of TiN coated films. The erosion-corrosion and corrosion resistance of (115) textured surface is better than that of (111) textured surface of TiN coated films

Notes: The purpose of this study is to figure out the effect of maintaining period of PTFE membrane used in GBR with autogeonous bone, heterogeneous bone and synthetic bone on bone formation on rabbits' cranial defect. Eight adult New Zealand white rabbits were used in this study. Four defects were surgically made in their calvaria. Using a trephine bur, 4 'through and through' defects were created and classified into 4 groups, which were consisted of control (no graft), experimental group 1 (autogeonous bone) and experimental group 2 (deproteinized bovine bone: OCS-B®; NIBEC, Korea), experimental group 3 (synthetic bone: MBCP; Biomatlante, France). The defects were covered with PTFE membrane (Cytoplast®, Innova, Canada). Membranes were removed after 1, 2, 4 and 8 weeks post-GBR in each 2 rabbits. And then, all rabbits were sacrificed; specimens were taken and observed histologically..: After removing the membranes after 1 week of the experiment, bone formation was not evident in a control group but the area was replaced with only loose fibrous connective tissue. In group 1(autogeonous bone), thin bone formation and infiltration of connective tissue on the superficial layer were observed. Initial bone formation and infiltration of fibrous connective tissue were evident in group 2(deprotenized bovine bone) and 3(synthetic bone). When the membranes were removed after 2 weeks of the experiment, bridge shaped bone formation was shown in control group but mostly connective tissue took place. More increased bone thickness was evident in group 1 and increased bone formation than first week was shown in group 2 and 3. When the membranes were removed after 4 weeks of the experiment, 2/3 of normal bone thickness was formed in control group still with infiltration of connective tissue. In group 1, regular bone formation with normal bone thickness was shown and in group 2 and 3, similar bone thickness to the normal was evident. After the removal of the membranes in 8 weeks, bone thickness formed in control group was more increased than 4th week, but could not reach normal bone thickness. In group 1, normal bone thickness was formed and similar bone thickness to that of the normal was observed in group 2 and 3. Within the limited study, when performing the GBR procedure, at least 4-week period of the membrane retention is required, and more retention time of the xenograft or synthetic bone is needed than that of autogenous bone for better bone regeneration

Notes: Ultra-fine grained and high hardened Al sheet was obtained by Equal Channel AngularPressing (ECAP). During this process the microstructure, the hardness and the texture of AA 1050 Alalloy sheet are changed by a severe shear deformation. The plastic strain ratio after the ECAP andsubsequent heat-treatment condition was investigated in this study. It was found that the averager-value of the equal channel angular pressed and subsequent heat-treated specimen was 1.7 timeshigher than that of the initial Al sheet. This could be attributed to the various texture formationsthrough the ECAP and subsequent heat-treatment of AA 1050 Aluminum alloy sheets

Notes: By severe plastic deformation of metals, an ultra fine grain size can be obtained. In the present study an AA 1050 Aluminium alloy has been severe deformed by Equal channel angular pressing (ECAP). A study on the microstructure and the texture of the samples after ECAP and subsequent heat treatment has been carried out. The specimens after ECAP showed a very fine grain size, a decrease of 〈100〉 // ND, and an increase of 〈111〉 // ND textures. The {111}〈112〉, {123}〈634〉, {110}〈001〉, {112}〈111〉, {110}〈111〉, and {013}〈231〉 texture components were increased in the specimens after the ECAP and subsequent heat-treatment at 400° C for 1 hour. One of the most important properties in sheet metals is formability. The r-value or plastic strain ratio has been used as a parameter that expresses the formability of sheet metals. The change of the plastic strain ratios after the ECAP and subsequent heat-treatment conditions has been investigated and it was found that they were two times higher than those of the initial Al sheets. This could be attributed to the formation above texture components through the ECAP and subsequent heat-treatment