Abstract
The 9 $\mu\textrm{m}$ GaN films on sapphire substrate were grown by Hydride vapor phase epitaxy. Dislocation density of these GaN films was measured by TEM. GaN film with crack free and mirror surface was directly grown on sapphire substrate. The dislocation density of this GaN film was $2{\times}10^9/cm^2$. The surface of GaN film on patterned GaN layer also presented a smooth mirror. But a part of GaN surface included holes because of incomplete coalescence. The dislocation density of GaN film above the mask region was lower than that in the window region. Especially, the dislocation density in the region between mask center and window region was close to dislocation free. The average dislocation density of ELO GaN was $8{\times}10^7/cm^2$.
HVPE 법으로 sapphire 기판 위에 두께 9$\mu\textrm{m}$의 GaN film을 성장하였다. Sapphire위에 직접 성장된 GaN film은 crack free로 mirror surface를 나타내었고 dislocation density는 $2{\times}10^9/cm^2$이었다.$SiO_2$ mask pattern을 사용하여 성장된 ELO GaN film도 대부분이 mirror surface를 나타내었으나 표면 일부에서 coalescence가 덜 이루어져 stripe 방향으로 hole이 존재하였다. ELO GaN film의 mask 윗부분은 window 부분에 비해 낮은 dislocation density를 나타냈다. 특히 mask center와 window사이 영역에서는 거의 dislocation이 없었다. ELO GaN film의 dislocation density는 평균 $8{\times}10^7/cm^2$.이었다.