ABSTRACT
Suk-Ki Min, Jong H. Lyou* School of Natural Science, Korea University, Chungnam, 339-800 Korea
Abstract. We applied a sublimation technique to prepare GaN on different types of substrates of porous silicon, poly-crystalline silicon, sapphire, and MOCVD deposited GaN on sapphire (MOCVDGaN/sapphire). X-ray diffraction (XRD) and scanning electron micrographs (SEM) indicate that GaN crystals are formed laterally with preferential (0002) and (0004) orientations parallel to the substrate plane and with a pyramid shape in the direction of c-axis with a hexagonalclosed pack structure for the MOCVD-GaN/sapphire. And photoluminescence (PL) shows the GaN sublimated on MOCVDGaN/sapphire has a superior PL efficiency to the one on sapphire. Finally, metal organic chemical vapor deposition (MOCVD) is applied to the GaN prepared with the method of sublimation (sublimatedGaN/MOCVD-GaN/sapphire). 1
1. Introduction GaN is one of most promising materials for optoelectronic devices and has been a subject for its growth during last decades. Accordingly, an effort is made to find a growth technique, and proves metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) would successfully grow GaN on sapphire [1]. However, there still remains a problem in getting high quality GaN, which is limited with the high density of the dislocation and the strain due to large differences in lattice constants and thermal expansion coefficients between hetero-epilayer and substrate [2], with such heteroepitaxial growth techniques. Thus the best GaN is prepared with a homoepitaxial growth [3].
