Four-inch high quality crack-free AlN layer grown on a high-temperature annealed AlN template by MOCVD

2021 ◽  
Vol 42 (12) ◽  
pp. 122804
Author(s):  
Shangfeng Liu ◽  
Ye Yuan ◽  
Shanshan Sheng ◽  
Tao Wang ◽  
Jin Zhang ◽  
...  
Keyword(s):  
High Temperature ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Flat Surface ◽  
Epitaxial Lateral Overgrowth ◽  
High Temperature Annealing ◽  
High Quality ◽  
High Crystalline Quality ◽  
X Ray ◽  
Lateral Overgrowth

Abstract In this work, based on physical vapor deposition and high-temperature annealing (HTA), the 4-inch crack-free high-quality AlN template is initialized. Benefiting from the crystal recrystallization during the HTA process, the FWHMs of X-ray rocking curves for (002) and (102) planes are encouragingly decreased to 62 and 282 arcsec, respectively. On such an AlN template, an ultra-thin AlN with a thickness of ~700 nm grown by MOCVD shows good quality, thus avoiding the epitaxial lateral overgrowth (ELOG) process in which 3–4 μm AlN is essential to obtain the flat surface and high crystalline quality. The 4-inch scaled wafer provides an avenue to match UVC-LED with the fabrication process of traditional GaN-based blue LED, therefore significantly improving yields and decreasing cost.

Comparison of Electron-Beam Physical Vapor Deposition and Plasma-Spray Physical Vapor Deposition Thermal Barrier Coating Properties Using Synchrotron X-Ray Diffraction

2019 ◽  
Author(s):  
Matthew Northam ◽  
Lin Rossmann ◽  
Brooke Sarley ◽  
Bryan Harder ◽  
Jun-Sang Park ◽  
...  
Keyword(s):  
Electron Beam ◽  
High Temperature ◽  
Plasma Spray ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Thermal Barrier ◽  
Jet Engines ◽  
X Ray Diffraction ◽  
X Ray

Abstract Electron-beam physical vapor deposition (EB-PVD) is widely used for the application of thermal barrier coatings (TBCs) to turbine blades in jet engines. An emerging method, plasma-spray physical vapor deposition (PS-PVD), is a hybrid technique whereby coatings can be applied via the liquid phase to form lamellar microstructures or via the vapor to form columnar microstructures similar to that of EB-PVD. In this study, PS-PVD and conventional EB-PVD coated samples of a columnar configuration were prepared and thermally cycled to 300 and 600 cycles. These samples were subsequently characterized in-situ, under thermal load using synchrotron x-rays. From the high-resolution x-ray diffraction (XRD) patterns, the residual and in-situ strain in the TGO layer was obtained during a thermal cycle. At high temperature, the TGO layer for both deposition methods displayed a constant near zero-strain for all samples as anticipated. In the samples with 300 thermal cycles, both deposition methods showed similar strain profiles in the TGO layer. For samples with 600 cycles, PS-PVD samples showed a more significant strain relief in the TGO at room temperature compared to similarly cycled EB-PVD samples. This could explain the coating lifetime performance between the two deposition methods. The findings support ongoing efforts to tune the manufacturing of PS-PVD coatings towards the goal of meeting or exceeding the performance of currently used coatings on jet engines. This will pave the way for more affordable high temperature coating alternatives that meet durability needs.

High Quality GaAs Mis Diodes With Very Low Surface State Density

1990 ◽  
Vol 209 ◽  
Author(s):  
Yoshihisa Fujisaki ◽  
Sumiko Sakai ◽  
Saburo Ataka ◽  
Kenji Shibata
Keyword(s):  
Chemical Vapor Deposition ◽  
Density Of States ◽  
Vapor Deposition ◽  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
State Density ◽  
High Quality ◽  
Metal Insulator ◽  
X Ray ◽  
Mis Devices

ABSTRACTHigh quality GaAs/SiO2 MIS( Metal Insulator Semiconductor ) diodes were fabricated using (NH4)2S treatment and photo-assisted CVD( Chemical Vapor Deposition ). The density of states at the GaAs and SiO2 interface is the order of 1011 cm-2eV-1 throughout the forbidden energy range, which is smaller by the order of two than that of the MIS devices made by the conventional CVD process. The mechanism attributable to the interface improvement was investigated through XPS( X-ray Photoelectron Spectroscopy ) analyses.

Influence of High Temperature Annealing on Microstructure Evolution of Ni-24Fe-14Cr-8Mo Superalloy

2021 ◽  
Vol 904 ◽  
pp. 117-123
Author(s):  
Yi Cui ◽  
Yun Fei Zhang ◽  
Yan Guang Han ◽  
Da Lv
Keyword(s):  
High Temperature ◽  
Microstructure Evolution ◽  
Testing Machine ◽  
Aging Treatment ◽  
Growth Patterns ◽  
High Temperature Annealing ◽  
Rockwell Hardness ◽  
Hardness Testing ◽  
X Ray Diffraction ◽  
X Ray

The effect of high temperature annealing on microstructure evolution of Ni-24Fe-14Cr-8Mo alloy was investigated through Optical Microscopy (OM), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Rockwell Hardness Testing Machine. Three kinds of grain growth patterns were found at different annealing temperatures due to carbides precipitation and dissolution. After a combination of high temperature annealing and aging treatment, the hardness versus time curves performed a parabolic pattern. The highest hardness was achieved under 1070°C/60 minutes treatment, and the desirable annealing time should be 60 minutes to 90 minutes.

scholarly journals The Progress on Low-Cost, High-Quality, High-Temperature Superconducting Tapes Deposited by the Combustion Chemical Vapor Deposition Process

2001 ◽  
Vol 689 ◽  
Author(s):  
Shara S. Shoup ◽  
Marvis K. White ◽  
Steve L. Krebs ◽  
Natalie Darnell ◽  
Adam C. King ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
High Temperature ◽  
Critical Current Density ◽  
Buffer Layer ◽  
Critical Current ◽  
Vapor Deposition ◽  
Low Cost ◽  
Chemical Vapor ◽  
High Critical Current Density ◽  
High Quality

ABSTRACTThe innovative Combustion Chemical Vapor Deposition (CCVD) process is a non-vacuum technique that is being investigated to enable next generation products in several application areas including high-temperature superconductors (HTS). In combination with the Rolling Assisted Biaxially Textured Substrate (RABiTS) technology, the CCVD process has significant promise to provide low-cost, high-quality lengths of YBCO coated conductor. The CCVD technology has been used to deposit both buffer layer coatings as well as YBCO superconducting layers. A buffer layer architecture of strontium titanate and ceria have been deposited by CCVD on textured nickel substrates and optimized to appropriate thicknesses and microstructures to provide templates for growing PLD YBCO with high critical current density values. The CCVD buffer layers have been scaled to meter plus lengths with good epitaxial uniformity along the length. A short sample cut from one of the lengths enabled high critical current density PLD YBCO. Films of CCVD YBCO superconductors have been grown on single crystal substrates with critical current densities over 1 MA/cm2. Work is currently in progress to combine both the buffer layer and superconductor technologies to produce high-quality coupons of HTS tape made entirely by the non-vacuum CCVD process.

scholarly journals Generation of Charged Ti Nanoparticles and Their Deposition Behavior with a Substrate Bias during RF Magnetron Sputtering

Coatings ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 443
Author(s):  
Ji-Hye Kwon ◽  
Du-Yun Kim ◽  
Nong-Moon Hwang
Keyword(s):  
Electron Microscopy ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Film Growth ◽  
Film Deposition ◽  
Calculated Density ◽  
X Ray ◽  
Positively Charged ◽  
Made In ◽  
Ti Films

This study is based on the film growth by non-classical crystallization, where charged nanoparticles (NPs) are the building block of film deposition. Extensive studies about the generation of charged NPs and their contribution to film deposition have been made in the chemical vapor deposition (CVD) process. However, only a few studies have been made in the physical vapor deposition (PVD) process. Here, the possibility for Ti films to grow by charged Ti NPs was studied during radio frequency (RF) sputtering using Ti target. After the generation of charged Ti NPs was confirmed, their influence on the film quality was investigated. Charged Ti NPs were captured on amorphous carbon membranes with the electric bias of −70 V, 0 V, +5 V, +15 V and +30 V and examined by transmission electron microscopy (TEM). The number density of the Ti NPs decreased with increasing positive bias, which showed that some of Ti NPs were positively charged and repelled by the positively biased TEM membrane. Ti films were deposited on Si substrates with the bias of −70 V, 0 V and +30 V and analyzed by TEM, field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and X-ray reflectivity (XRR). The film deposited at −70 V had the highest thickness of 180 nm, calculated density of 4.974 g/cm3 and crystallinity, whereas the film deposited at +30 V had the lowest thickness of 92 nm, calculated density of 3.499 g/cm3 and crystallinity. This was attributed to the attraction of positively charged Ti NPs to the substrate at −70 V and to the landing of only small-sized neutral Ti NPs on the substrate at +30 V. These results indicate that the control of charged NPs is necessary to obtain a high quality thin film at room temperature.

scholarly journals Исследование нелегированных нанокристаллических алмазных пленок, выращенных из газовой фазы в плазме СВЧ разряда

2021 ◽  
Vol 55 (1) ◽  
pp. 49
Author(s):  
А.Л. Вихарев ◽  
С.А. Богданов ◽  
Н.М. Овечкин ◽  
О.А. Иванов ◽  
Д.Б. Радищев ◽  
...  
Keyword(s):  
High Temperature ◽  
Vapor Deposition ◽  
Microwave Plasma ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Inert Gas ◽  
Dielectric Films ◽  
High Temperature Annealing ◽  
Structural And Electrical Properties ◽  
Methane Mixture

Undoped nanocrystalline diamond (NCD) films less than 1 μm thick grown on Si (100) silicon by microwave plasma-assisted chemical vapor deposition at a frequency of 2.45 GHz are studied. To obtain diamond dielectric films with maximum resistivity the deposition of films in three gas mixtures is investigated: hydrogen-methane mixture, hydrogen-methane mixture with the addition of oxygen and hydrogen-methane mixture with the addition of an inert gas. A relationship has been established between the growth conditions, structural and electrical properties of NCD films. It is shown that for the use of NCD films as effective dielectrics preliminary high-temperature annealing of the films is required, for example, in vacuum at a temperature of 600°C for one hour.

Strain Tolerance and Microstructure of Thermal Barrier Coatings Produced by Electron Beam Physical Vapor Deposition Process

2006 ◽  
Vol 522-523 ◽  
pp. 267-276 ◽  
Author(s):  
Kunihiko Wada ◽  
Yutaka Ishiwata ◽  
Norio Yamaguchi ◽  
Hideaki Matsubara
Keyword(s):  
Electron Beam ◽  
High Temperature ◽  
Thermal Barrier Coatings ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Aging Treatment ◽  
Nanoindentation Test ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Strain Tolerance

Several kinds of thermal barrier coatings (TBCs) deposited by electron beam physical vapor deposition (EB-PVD) were produced as a function of electron beam power in order to evaluate their strain tolerance. The deposition temperatures were changed from 1210 K to 1303 K depending on EB power. In order to evaluate strain tolerances of the EB-PVD/TBCs, a uniaxial compressive spallation test was newly proposed in this study. In addition, the microstructures of the layers were observed with SEM and Young’s moduli were measured by a nanoindentation test. The strain tolerance in as-deposited samples decreased with an increase in deposition temperature. In the sample deposited at 1210 and 1268 K, high-temperature aging treatment at 1273 K for 10 h remarkably promoted the reduction of the strain tolerance. The growth of thermally grown oxide (TGO) layer generated at the interface between topcoat and bondcoat layers was the principal reason for this strain tolerance reduction. We observed TGO-layer growth even in the as-deposited sample. Although the thickness of the initial TGO layer in the sample deposited at high temperature was thicker, the growth rate during aging treatment was smaller than those of the other specimens. This result suggests that we can improve the oxidation resistance of TBC systems by controlling the processing parameters in the EB-PVD process.

Investigations of Crystalline Phases in Glasses under Various Annealing Conditions

2020 ◽  
Vol 28 ◽  
pp. 14-19
Author(s):  
Zamir V. Shomakhov ◽  
Akhmed M. Karmokov ◽  
Oleg A. Molokanov ◽  
Olga O. Molokanova ◽  
Rita Y. Karmokova ◽  
...  
Keyword(s):  
High Temperature ◽  
Structural Changes ◽  
Irreversible Processes ◽  
High Temperature Annealing ◽  
X Ray Diffraction ◽  
Structural And Phase Transformations ◽  
X Ray ◽  
Air Atmosphere ◽  
Annealing Conditions ◽  
Microchannel Plates

Studies of the temperature dependence of the electrical properties of glasses show that the high-temperature annealing in glasses observed irreversible processes. These processes lead to changes in electrical conductivity, dielectric permittivity, and hence the electrical capacitance, dielectric loss tangent, and other parameters. Obviously, this is due to structural changes in the glass as a result of high-temperature annealing. In this regard, this paper presents studies of structural and phase transformations in glasses used for the production of microchannel plates in the process of high-temperature annealing in vacuum and in the air atmosphere at different times. The studies were conducted by x-ray phase and X-ray diffraction analysis, as well as X-ray fluorescence elemental analysis.

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