Abstract Combination of sputter deposition and high-temperature annealing is a promising technique for preparing AlN templates with low threading dislocation density (TDD) at lower film thickness compared to those prepared by the conventional metalorganic vapor phase epitaxy. However, cracking films during critical issue. In this study, we controlled residual stress sputter-deposited modifying sputtering conditions. Consequently, occurrence was effectively suppressed. By optimizing...

AlGaN films were grown on face-to-face annealed sputter-deposited AlN/sapphire (FFA Sp-AlN) templates via metalorganic vapor phase epitaxy (MOVPE), and the growth behavior of was investigated. The sapphire substrates with small off-cut exhibited poor surface flatness FFA Sp-AlN owing to formation large hillock structures. To understand origin these structures, crystallinity morphology conventional fully MOVPE-grown (MOVPE-AlN) template comprehensively studied. screw- mixed-type threading...

Abstract Regarding deep-ultraviolet optical device applications, face-to-face annealed sputter-deposited AlN (FFA Sp-AlN) is a promising alternative to the conventional metalorganic vapor phase epitaxy (MOVPE)-prepared templates on sapphire substrates. However, FFA Sp-AlN tends exhibit AlGaN growth-related hillock generation and surface morphology deterioration. In this study, we optimized sputter-deposition conditions for MOVPE growth respectively reduce density size. After confirming...

AlN on sapphire with dislocation density of 107 cm−2 was prepared by double sputtering and annealing processes. Full width at half maximum values X-ray rocking curve for diffractions the films were measured to be 10–20 arcsec 65–82 arcsec, respectively. Dislocations characterized plan-view cross-sectional transmission electron microscopy, total estimated as 4.3 × cm−2. A polarity inversion layer found between two sputtered layers, which increased possibility blocking dislocations stemming...

Abstract Thermal cycle annealing (TCA) is introduced to accelerate the dislocation annihilation in sputter-deposited AlN films on sapphire. Compared with constant temperature annealing, processed by TCA showed lower densities, smoother surface morphology, and fewer defects generated from AlN/sapphire interface. After optimizing film thickness, a thickness of 800 nm, X-ray rocking curve full widths at half maximum 10–20 arcsec (0002) 80–90 (10-12) were demonstrated, providing simple low-cost...

We have grown blue light-emitting diodes (LEDs) having InGaN/GaN multi-quantum wells (MQWs) with thin AlyGa1−yN (0 < y 0.3) interlayers on Si(111) substrates. It was found by high-resolution transmission electron microscopy observations and three-dimensional atom probe analysis that 1-nm-thick an AlN mole fraction of less than = 0.3 were continuously formed between GaN barriers InGaN wells, the up to 0.15 could be consistently controlled. The external quantum efficiency LED enhanced...

Vacancy-type defects in AlN films were probed by using monoenergetic positron beams. The deposited on sapphire substrates a radio-frequency sputtering technique. Epitaxial grown metalorganic vapor phase epitaxy the sputtered also characterized. For AlN, major defect species was identified to be complexes between Al-vacancy and oxygen atoms located at nitrogen sites. Vacancy clusters introduced after annealing 1300 °C N2 atmosphere but their concentration decreased with higher temperature....

This study comprehensively investigates the properties of metalorganic vapor phase epitaxy (MOVPE)‐grown AlN films on high‐quality face‐to‐face annealed sputtered (FFA Sp‐AlN) templates sapphire substrates, which are highly important to control surface morphology for various applications, such as UV light‐emitting diodes and laser diodes. The conditions thermal cleaning growth by MOVPE investigated remove numerous small islands as‐annealed FFA Sp‐AlN. Subsequent in H 2 + NH 3 at 1300 °C, is...

Abstract AlN templates fabricated via a combination of sputtering deposition and post-deposition high-temperature face-to-face annealing can be applied to deep-ultraviolet (DUV) light-emitting devices because their extremely low threading dislocation density (TDD) despite low-cost simple fabrication process. First, this paper summarizes the overview essential crystalline characteristics annealed sputter-deposited template (FFA Sp-AlN). Thereafter, recent progress in TDD reduction FFA Sp-AlN...

Institute of Space and Astronautical Science (ISAS/JAXA) in collaboration with Mitsubishi Heavy Industries (MHI) has developed fuel gas tanks for reaction control system orbital satellites; A tank is fabricated through welding two thin, hemi-spherical or conical parts, which are by superplastic blow forming. Mass-productivity not an important factor but the forming precision flexibiliry process this application. ISAS MHI, therefore, a new blow-forming technique, high flexibility terms size...

The impact of a face-to-face annealed sputtered AlN/sapphire (FFA Sp-AlN) template with threading-dislocation densities (TDDs) 2 × 108 cm−2 and an n-type AlGaN (n-AlGaN) underlayer on optical properties multiple quantum wells (MQWs) ultraviolet C (UVC) emission is investigated comprehensively. For comparison the FFA Sp-AlN low TDDs, conventional MOVPE (metalorganic vapor phase epitaxially)-grown (MOVPE-AlN) TDDs 1 109 was prepared. Consequently, cathodoluminescence (CL),...

Abstract Reducing the average Al composition of x Ga 1− N/Al y N multiple quantum wells (MQWs) is an effective approach to increase current injection efficiencies far-UV-C LEDs (far-UVC LEDs). A reduction can be realized by decreasing Al-composition differentiation between well and barrier layers. Compared conventional MQWs, a 230 nm wavelength far-UVC LED equipped with single-Al-composition 39 thick light-emitting layer exhibits higher external efficiency (EQE). The EQE low (∼1%) enhanced...

A crack-free aluminum nitride (AlN) layer of 9 ± 1 μm thickness was grown on a nanopatterned sapphire substrate (NPSS) with sputter-deposited AlN buffer layer. The thermally annealed and regrown by hydride vapor-phase epitaxy (HVPE). dependence the crystallinity HVPE-grown layers growth temperature investigated. It found that undesired misaligned can be prevented choosing an appropriate temperature. full widths at half maximum (0002)- (10–12)-plane X-ray rocking curves were improved to as...

Face-to-face annealed sputter-deposited aluminum nitride (AlN) templates (FFA Sp-AlN) are a promising material for application in deep-ultraviolet light-emitting diodes (DUV-LEDs), whose performance is directly related to the crystallinity of AlN film. However, influence sputtering conditions and annealing on films have not yet been comprehensively studied. Accordingly, this study, we fabricate sapphire substrates through deposition followed by face-to-face high-temperature annealing,...