2020, Vol.30, No.3

Journal of the Korean Crystal Growth and Crystal Technology 2023 KCI Impact Factor : 0.19

pISSN : 1225-1429 / eISSN : 2234-5078
https://journal.kci.go.kr/jkcgct

The effect of substrate surface roughness and sintering temperature on the adhesion strength of Ag-based thick film conductors formed on AlN substrates with excellent thermal conductivity was studied. The adhesion strength of the thick-film conductor manufactured using an AlN substrate having a surface roughness (Ra) of 0.5 was higher than that of a thick-film conductor manufactured using a substrate having a surface roughness greater or smaller than this. In the case of a substrate with a surface roughness of less than 0.5, the contact area between the Ag thick film conductor and the substrate was relatively smaller than that of a substrate with a surface roughness of 0.5, resulting in a lower adhesive strength. On the other hand, when a substrate having a surface roughness of more than 0.5 was used, it was found that the conduct or film was not completely adhered to the substrate, and as a result, it was found that the adhesive strength was small. In addition, it was found that the surface smoothness of the Ag-based thick film conductor film obtained by sintering at 850°C was the best compared to the smoothness of the conductor film obtained by sintering at different sintering temperatures,and as a result, it was found that the adhesive strength of the conductor film was the highest.

In this study, we report a hydrothermal synthesis in which BaTiO3 nanoparticles (NPs) with enhanced size uniformity and dispersibility are synthesized by increased time and temperature, increasing nucleation and diffusion rates. The formation process of an uniform size of 20 nm BaTiO3 NPs, which has not been extensively researched, was optimized through hydrothermal synthesis at 180°C. Simultaneous increase in the nucleation rate of TiO2 and diffusion length of Ba2+ ions, resulting from a higher temperature, allowed for the synthesis of BaTiO3 NPs (20 nm) with significantly enhanced size-uniformity. The size and crystallinity of BaTiO3 NPs which exhibit excellent dispersibility in hexane solvent were investigated using transmission electron microscopy and X-ray diffraction. The results presented herein provide insights into improving the size uniformity and dispersibility of BaTiO3 NPs by hydrothermal synthesis for applications to variety of electronic devices.

In this paper, AlN epilayers on 6H-SiC (0001) substrate are grown by mixed source hydride vapor phase epitaxy(MS-HVPE). AlN epilayer of 0.5 μm thickness was obtained with a growth rate of 5 nm per hour. The surface of AlN epilayergrown on 6H-SiC (0001) substrate was investigated by field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS). Dislocation density was considered through HR-XRD and related calculations. A fine crystalline AlN epilayer with screw dislocation density of 1.4 × 10⁹cm⁻² and edge dislocation density of 3.8 × 10⁹cm⁻² was confirmed. The AlN epilayer on 6H-SiC (0001) substrate grown by using the mixed source HVPE method could be applied to power devices.