2016, Vol.26, No.2

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

6H-SiC single crystals were grown by using a resistance heating system. It was recognized that the growth behavior was different according to the different growth temperatures. It was revealed that the temperatures at the source feeding and at the crystal growth position had to be controlled independently. In this report, the effect of growth temperature on the SiC crystal growth was discussed.

Bulk GaN crystals were grown by the basic ammonothermal method. The c-plane GaN templates grown by hydride vapor phase epitaxy were used as seed crystals and sodium metal, amide, and azide were added as a mineralizer. The growth conditions are at temperatures from 500~600 o C and pressures from 2~3 kbar. The growth rate for the c-axis was increased with increasing the operating pressure. Average dislocation density was measured 1 × 10 5 /cm 2 by the cathodoluminescence measurement. The full-width at half-maximum of the X-ray diffraction rocking curve for (002) reflection was approximately 270 arcsec for Ga face and 80 arcsec for N face.

In this study, it was investigated that characteristic of crack-self-healing of hot-pressed SiC. SiC ceramics was sintered with Al2O3 and Y2O3 sintering additive by hot press. Sintering was performed in hot-press furnace in flowing argon (Ar), holding for 3 hr under 1950 o C and 50 MPa. The sintered SiC was machined into 3-point bending strength specimen of 3 × 4 × 40 mm, and introduced pre-crack by Vickers indentation at 49.6 N. Specimens were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), 3-point bending strength after heat treatment at 1200~1400 o C for 1~10 hr. The best crack-self-healing ability was achieved 770 MPa 3-point bending strength by heat treatment at 1300 o C for 5 hr.