Analysis of the Defect Structure of Epitaxial GaN

Analysis of threading dislocations in void shape controlled GaN re-grown on hexagonally patterned mask-less GaN

“…Twist is associated to the inplane rotation of the mosaic structures and it is caused by the presence of edge-and mixed-type TDs. Twist is usually measured with o-scans taken in off-axis rotation [31,32]. For the estimation of twist in our samples, the FWHM of o-scans have been measured from 201 and 121 reflections.…”

Maskless pendeo-epitaxial growth of GaN films

“…The full-width half-maximum (FWHM) values of the rocking curves in the on-axis (0002) reflection indicate the concentration of screw-type dislocations, while values of off-axis (30:3 -0) FWHM determine the relative density of edge-type dislocations. 33 A reduction in screw-type dislocations in the wings with respect to the stripes is indicated by a reduction in FWHM of the (0002) reflections from 646 arcsec to 354 arcsec. The off-axis FWHM of the wing area was 126 arcsec compared to 296 arcsec for the stripe, indicating a reduction in the edge-type dislocations as well.…”

Buffer-layer-free growth of high-quality epitaxial GaN films on 4H-SiC substrate by metal-organic chemical vapor deposition

“…Therefore, the buffer layer must be a discontinuous film and hence the main growth on it cannot have a high crystalline quality. The film quality of GaN was greatly improved at a reduced pressure and the more excess Ga condition (sample G) compared to that of sample F. In the case of GaN, the edge dislocation density ($10 9 -10 10 cm À2 ) was found to be higher than the screw dislocation density ($10 8 cm À2 ) [18][19][20]. It is well known that line broadening (FWHM) of the symmetric (0 0 0 2) reflection is mainly caused by screw dislocations with the Burgers vector b ¼ ½0 0 0 1; while those of the asymmetric reflections such as ð1 01 3Þ; and ð3 03 2Þ are induced by edge dislocations with b ¼ 1=3ð1 12 0Þ as well as screw dislocations [21].…”