TY - JOUR
T1 - Threading dislocations in heteroepitaxial AlN layer grown by MOVPE on SiC (0 0 0 1) substrate
AU - Taniyasu, Yoshitaka
AU - Kasu, Makoto
AU - Makimoto, Toshiki
PY - 2007/1/1
Y1 - 2007/1/1
N2 - To clarify the mechanisms governing the formation and reduction of threading dislocations (TDs) in aluminum nitride (AlN) layers grown on SiC (0 0 0 1) substrates by metalorganic vapor phase epitaxy (MOVPE), we characterized the mosaicity and the growth mode. High-density (∼1011 cm-2) three-dimensional (3D) AlN islands nucleate on the substrate. Because the islands are slightly misoriented with respect to each other, dislocations are generated with a high density of 1010-1011 cm-2 as the islands coalesce. However, most of the dislocations are annihilated because their propagation direction changes horizontally during the island growth. Thus, at the initial growth stage, the dislocation density is drastically decreased to 108-109 cm-2. Consequently, as the layer thickness increases, the defect-free region becomes larger and the misorientation becomes smaller. On the other hand, we found that the TDs induce a large tensile strain and that the residual strain decreases with decreasing dislocation density. From the relationship between a- and c-lattice strains, the Poisson ratio of AlN was determined to be 0.19.
AB - To clarify the mechanisms governing the formation and reduction of threading dislocations (TDs) in aluminum nitride (AlN) layers grown on SiC (0 0 0 1) substrates by metalorganic vapor phase epitaxy (MOVPE), we characterized the mosaicity and the growth mode. High-density (∼1011 cm-2) three-dimensional (3D) AlN islands nucleate on the substrate. Because the islands are slightly misoriented with respect to each other, dislocations are generated with a high density of 1010-1011 cm-2 as the islands coalesce. However, most of the dislocations are annihilated because their propagation direction changes horizontally during the island growth. Thus, at the initial growth stage, the dislocation density is drastically decreased to 108-109 cm-2. Consequently, as the layer thickness increases, the defect-free region becomes larger and the misorientation becomes smaller. On the other hand, we found that the TDs induce a large tensile strain and that the residual strain decreases with decreasing dislocation density. From the relationship between a- and c-lattice strains, the Poisson ratio of AlN was determined to be 0.19.
KW - A1. X-ray diffraction
KW - A3. Metalorganic vapor phase epitaxy
KW - B1. Nitrides
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U2 - 10.1016/j.jcrysgro.2006.10.032
DO - 10.1016/j.jcrysgro.2006.10.032
M3 - Article
AN - SCOPUS:33846442038
VL - 298
SP - 310
EP - 315
JO - Journal of Crystal Growth
JF - Journal of Crystal Growth
SN - 0022-0248
IS - SPEC. ISS
ER -