Effect of annealing time and pressure on electrical activation and surface morphology of Mg-implanted GaN annealed at 1300 °C in ultra-high-pressure nitrogen ambient

2021 ◽  
Author(s):  
Kensuke Sumida ◽  
Kazufumi Hirukawa ◽  
Hideki Sakurai ◽  
Kacper Sierakowski ◽  
Masahiro Horita ◽  
...  
Keyword(s):  
High Pressure ◽  
Surface Morphology ◽  
Isothermal Annealing ◽  
Nitrogen Pressure ◽  
Electrical Activation ◽  
Ultra High Pressure ◽  
Compensation Ratio ◽  
Annealing Study ◽  
Inner Diameter ◽  
Activation Ratio

Abstract We performed an isothermal annealing study on Mg-implanted GaN at 1300 °C in an ultra-high-pressure (1 GPa) nitrogen ambient. Annealing for more than 30 min resulted in a high acceptor activation ratio and a low compensation ratio that were comparable to those obtained with annealing at 1400 °C for 5 min. We also performed annealing at 1300 °C in a reduced nitrogen pressure of 300 MPa which makes us possible to expand inner diameter of annealing equipment in the future. High electrical activation, similar to one obtained by annealing at 1 GPa, was successfully obtained.

scholarly journals Effects of ultra-high-pressure annealing on characteristics of vacancies in Mg-implanted GaN studied using a monoenergetic positron beam

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Akira Uedono ◽  
Hideki Sakurai ◽  
Tetsuo Narita ◽  
Kacper Sierakowski ◽  
Michal Bockowski ◽  
...  
Keyword(s):  
High Pressure ◽  
Positron Beam ◽  
Nitrogen Pressure ◽  
Defect Concentration ◽  
Hydrogen Atoms ◽  
Capping Layer ◽  
Ultra High Pressure ◽  
Defect Species ◽  
Major Defect ◽  
Diffusion Properties

Abstract Vacancy-type defects in Mg-implanted GaN were probed by using a monoenergetic positron beam. Mg ions were implanted into GaN to obtain 0.3-μm-deep box profiles with Mg concentrations of 1 × 1019 cm−3. The major defect species in an as-implanted sample was determined to be Ga-vacancy related defects such as a complex between Ga and N vacancies. The sample was annealed under a nitrogen pressure of 1 GPa in a temperature range of 1000–1480 °C without a protective capping layer. Compared with the results for Mg-implanted GaN annealed with an AlN capping layer, the defect concentration was decreased by the cap-less annealing, suggesting that the surface of the sample was an effective sink for vacancies migrating toward the surface. Depth distributions of Mg after annealing above 1300 °C were influenced by the presence of residual vacancies at this temperature. Hydrogen atoms were unintentionally incorporated into the sample during annealing, and their diffusion properties were also affected by both vacancies and Mg.

Wear behavior of friction pairs of different materials for ultra-high-pressure axial piston pump

2018 ◽  
Vol 233 (5) ◽  
pp. 945-953 ◽  
Author(s):  
Jin Zhang ◽  
Xiaogang Qiu ◽  
Xuezhi Gong ◽  
Xiangdong Kong
Keyword(s):  
High Pressure ◽  
Friction Coefficient ◽  
Surface Morphology ◽  
Ceramic Materials ◽  
Piston Pump ◽  
Wear Testing ◽  
Axial Piston Pump ◽  
Ultra High Pressure ◽  
Two Samples ◽  
Axial Piston

This paper evaluates the wear of two different materials (ceramic and 30Cr2MoVA) of friction pairs of ultra-high-pressure axial piston by means of experimental investigations. Face sliding wear test was carried out on wear testing machine to analyze the coefficient of friction during boundary friction. Then wear amount of the sample is obtained by weighing with the electronic balance. The change of the surface morphology was observed by a laser confocal microscope. By comparing the friction coefficient, wear amount, surface morphology, temperature change, and roughness of the two samples, it has been found that ceramic materials have lower friction coefficient, better wear resistance, and less oil temperature rise than 30Cr2MoVA material. By the above research results it was found that ceramic materials perform better than 30Cr2MoVA, which provides the foundation for further study of the friction pair of the ultra-high-pressure axial piston pump.

Isochronal annealing study of Mg-implanted p-type GaN activated by ultra-high-pressure annealing

2021 ◽  
Author(s):  
Kazufumi Hirukawa ◽  
Kensuke Sumida ◽  
Hideki Sakurai ◽  
Hajime FUJIKURA ◽  
Masahiro Horita ◽  
...  
Keyword(s):  
High Pressure ◽  
Isochronal Annealing ◽  
Ultra High Pressure ◽  
Annealing Study ◽  
P Type

scholarly journals Trans-lithospheric diapirism explains the presence of ultra-high pressure rocks in the European Variscides

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Petra Maierová ◽  
Karel Schulmann ◽  
Pavla Štípská ◽  
Taras Gerya ◽  
Ondrej Lexa
Keyword(s):  
High Pressure ◽  
Numerical Models ◽  
Classical Concept ◽  
Plate Interface ◽  
Ultra High Pressure ◽  
Common Process ◽  
Mountain Belts ◽  
Collisional Orogens ◽  
Rock Association ◽  
European Variscides

AbstractThe classical concept of collisional orogens suggests that mountain belts form as a crustal wedge between the downgoing and overriding plates. However, this orogenic style is not compatible with the presence of (ultra-)high pressure crustal and mantle rocks far from the plate interface in the Bohemian Massif of Central Europe. Here we use a comparison between geological observations and thermo-mechanical numerical models to explain their formation. We suggest that continental crust was first deeply subducted, then flowed laterally underneath the lithosphere and eventually rose in the form of large partially molten trans-lithospheric diapirs. We further show that trans-lithospheric diapirism produces a specific rock association of (ultra-)high pressure crustal and mantle rocks and ultra-potassic magmas that alternates with the less metamorphosed rocks of the upper plate. Similar rock associations have been described in other convergent zones, both modern and ancient. We speculate that trans-lithospheric diapirism could be a common process.

scholarly journals Advances in ultra‐high‐pressure and multi‐dimensional liquid chromatography instrumentation and workflows

2021 ◽  
Author(s):  
Jelle De Vos ◽  
Dwight Stoll ◽  
Stephan Buckenmaier ◽  
Sebastiaan Eeltink ◽  
James P. Grinias
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Ultra High Pressure
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