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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Observation of Solder Layers for PJVS Chips Formed with Supersonic-Soldering Method
摘要： The InSn solder layers between Si chips for programmable Josephson voltage standard (PJVS) and sapphire substrates for thermal contact were observed using a scanning acoustic microscope. The solder layers were formed with a supersonic-soldering method in several conditions. Based on the results of the observations, the void ratio in the solder layers was estimated to be approximately 20 % – 40 %, which is much improved in comparison to that obtained with a conventional soldering method of approximately 80 %. We are now trying to measure the influence of these soldering methods on the thermal contact of PJVS chips.
关键词： void,InSn solder,thermal contact,Josephson voltage standard chip,supersonic solder,sapphire substrate
更新于2025-09-10 09:29:36
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Influence of quartz on silicon incorporation in HVPE grown AlN
摘要： Aluminum nitride growth via hydride vapor phase epitaxy has been investigated with respect to impurity uptake. The precursor aluminum chloride was identified to react with quartz glass and provide silicon into the reactor atmosphere and subsequently into grown AlN layers. Reactor parts made of quartz were consecutively replaced by carbon glass parts to prevent unintentional silicon incorporation into III-nitride layers during growth. Carbon glass substitution of quartz parts led to a reduction of silicon levels in AlN by three orders of magnitude to 4*1016 cm-3, while carbon concentration in grown AlN layers remained low in the range of 1017 cm-3.
关键词： A1. Substrate,B1. Nitrides,B2. Semiconducting III-V materials,A3. Hydride Vapor Phase Epitaxy,B1. Sapphire
更新于2025-09-09 09:28:46
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Suppressing the Initial Growth of Sidewall GaN by Modifying Micron-Sized Patterned Sapphire Substrate with H3PO4-Based Etchant
摘要： Micron-sized patterned sapphire substrates (PSS) are used to improve the performance of GaN-based light-emitting diodes (LEDs). However, the growth of GaN is initiated not only from the bottom c-plane but also from the sidewall of the micron-sized patterns. Therefore, the coalescence of these GaN crystals creates irregular voids. In this study, two kinds of nucleation layers (NL)—ex-situ AlN NL and in-situ GaN NL—were used, and the growth of sidewall GaN was successfully suppressed in both systems by modifying the micron-sized PSS surface.
关键词： growth of GaN,micron-sized patterned sapphire substrate,sidewall GaN
更新于2025-09-09 09:28:46
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Nanoelectronics and Materials Development || Epitaxial Cu3Ge Thin Film: Fabrication, Structure, and Property
摘要： In this paper, the fabrication and electrical property characterization of epitaxial Cu3Ge thin film are performed. By adjusting deposition parameters, the crystallinity of the as‐grown Cu3Ge thin films is improved, with the formation of twins within it. The average work function of epitaxial Cu3Ge thin film is measured to be ～4.47 + 0.02 eV, render‐ ing it a desirable mid‐gap gate metal for applications in complementary metal‐oxide semiconductor (CMOS) devices. The present study therefore shows an epitaxial Cu3Ge thin film that is promising for applications.
关键词： sapphire,semiconductor metallization,Cu3Ge thin film,pulsed laser deposition,twin
更新于2025-09-09 09:28:46
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Preparation and Properties of Sapphire by Edge-defined Film-fed Growth (EFG) Method with Different Growth Directions
摘要： Sapphire, belonging to hexagonal crystal system, is typically anisotropic which makes it direction-sensitive. To research the effects of growth directions on properties of sapphire, c-[0001] seed (c-sapphire) and a-[11-20] seed (a-sapphire) were used to prepare sapphire by edge-defined film-fed growth (EFG) method. The samples were analyzed through lattice integrity, dislocation and corrosion performance by double-crystal XRD, OM, AFM, SEM and EDX. It was shown that the lattice integrities of two growth-direction crystals were both well due to the small FWHM values. While the average densities of dislocation in c-sapphire and a-sapphire were 9.2×103 and 3.9×103 cm-2 respectively, the energy of dislocation in c-sapphire was lower than that in a-sapphire. During Strong Phosphoric Acid (SPA) etching, the surface of c-sapphire basically kept smooth but in a-sapphire there were many point-like corrosion pits where aluminum and oxygen atoms lost by 2:1. Our work means that it will be promising for growing c-[0001] seed sapphire by EFG if aided by parameter optimization.
关键词： sapphire,edge-defined film-fed growth,growth direction
更新于2025-09-09 09:28:46
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Experimental study of proton acceleration from thin-foil on a table top Ti:Sapphire
摘要： Table-top lasers of moderate energies (0.1- 0.5 J) are promising, cost-effective laser-driven sources of MeV-energy protons and ions accelerators, but many applications of laser-accelerated ion beams will not only require a low cost, compact system but also require operation at high repetition rates (>10 Hz). This paper focus the effort to characterize and optimize proton acceleration processes using 3 TW/55 fs, table-top Ti:Sapphire (Ti:Sa) laser capable to operate at 10 Hz, with this intention the maximum proton energy obtained, in a single shot, was evaluated by irradiating a variety of flat targets, from thin film to sub-micrometric film membranes designed for our purposes in a high density target array. The presented work is a previous stage and this study has the intention to be the prelude of the technological challenge, both in laser technology as well target design capable of operating at high repetition rates.
关键词： Ti:Sapphire laser,proton acceleration,thin-foil targets,high repetition rates
更新于2025-09-09 09:28:46
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Investigation of the Anisotropy of the Structural Properties of GaN(0001) Layers Grown by MOVPE on a-Plane (11$$\bar {2}$$0) Sapphire
摘要： The structural properties of GaN(0001) heteroepitaxial layers grown by metalorganic vapor phase epitaxy (MOVPE) on a-plane (11 0) sapphire substrates are investigated by X-ray diffractometry. Anisotropy of the rocking-curve width for the symmetric (0004) and asymmetric {11 4} and {10 5} reflections of gallium nitride upon rotation of the sample is observed. A comparison of the anisotropy of the rocking-curve width for GaN(0001)/Al2O3(11 0) layers with two different variants of in-plane orientation relationships suggests that the anisotropy of the structural properties is independent of the thermoelastic stress arising upon cooling the heterostructure.
关键词： structural properties,MOVPE,anisotropy,sapphire,GaN,X-ray diffractometry
更新于2025-09-09 09:28:46
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How to obtain metal-polar untwinned high-quality (1?0??1?3) GaN on m-plane sapphire
摘要： Directional sputtering of Al and AlN on (1 0 ?1 0) sapphire was used to obtain metal-polar (1 0 ?1 3) templates. After overgrowth with AlN and GaN using metal-organic vapor phase epitaxy, we obtained untwinned (1 0 ?1 3) GaN layers. Full width at half maximum of the X-ray rocking curve of symmetric (1 0 ?1 3) GaN is less than 550 arcsec along both [3 0 ?3 ?2]GaN and [1 ?2 1 0]GaN directions. Ga-polarity of the layers was con?rmed by high-resolution scanning transmission electron microscopy. Careful optimization of time and temperature of the initial Al sputtered layer was a key parameter to achieve high quality GaN templates.
关键词： Directional sputtering,Al nucleation layer,Metal polar,M-plane sapphire
更新于2025-09-04 15:30:14
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Effect of growth pressure on graphene direct growth on r-plane and c-plane sapphires by low-pressure CVD
摘要： Graphene was grown on both r-plane and c-plane sapphires by low-pressure chemical vapor deposition without using a metal catalyst. The growth pressure was systematically changed to investigate how the growth pressure effects the graphene growth. Consequently, it was found that the coverage of the graphene increased with increasing growth pressure on the r-plane sapphire while it decreased with increasing growth pressure on the c-plane sapphire. Raman spectroscopy and atomic force microscopy indicates that the growth layer is single-layer graphene on the r-plane sapphire while it is a bi-layer on the c-plane sapphire. Graphene is thought to grow on the r-plane sapphire simply in a two-dimensional nucleation mode. On the other hand, graphene tends to grow in the pits formed on the surface of the c-plane sapphire. The pits are thought to be produced by the oxygen desorption and have some catalytic effects.
关键词： sapphire,low-pressure CVD,atomic force microscopy,growth pressure,graphene,Raman spectroscopy
更新于2025-09-04 15:30:14