Defect structure of a free standing GaN wafer grown by the ammonothermal method

Observation of dislocations and their arrays in physical vapor transport-grown AlN single-crystal substrate by synchrotron X-ray topography

“…Classification of dislocations by the shape, size and bright/dark outlines of their XRT contrast has been reported for hexagonal crystals such as 4H-SiC 29,30) and GaN. 32,33) The results in the literature are in consistent with our previous studies, in which XRT images are compared with etch pits and TEM observation. 31,34) Among the four types of dislocation-related XRT contrast in Fig.…”

“…This technique has been widely used for 4H-SiC [29][30][31] and recently for GaN. [32][33][34] In this work, we have carried out XRT observation of an AlN bulk substrate. Representative dislocation contrast is discussed.…”

Correlation between structural properties and nonradiative recombination behaviors of threading dislocations in freestanding GaN substrates grown by hydride vapor phase epitaxy

“…14 In the case of ammonothermal FS-GaN, Sintonen et al reported percentages of 0%, 10%, and 90% for TEDs, TSDs, and TMDs, respectively, in a sample with a TD density of 3.5×10 4 cm -2 , 55 and 0%, 37%, and 63% in another sample with a TD density of 8.8×10 4 cm -2 . 6 Similar results for the ammonothermal FS-GaN were obtained in our previous study in which the Burgers vectors were determined using X-ray topography taken with 7 g vectors. 56 Compared to GaN thin films in early studies and FS-GaN grown by other methods, recent commercial HVPE substrates (TD density of ~10 6 cm -2 ) from several suppliers typically show a dominating TED percentage of approximately 70-80%.…”

“…2 To fully exploit the physical properties of GaN in such devices, there have been numerous efforts in recent years to develop high-quality and large-diameter freestanding GaN (FS-GaN) substrates, on which homoepitaxial growth of GaN layers with a low threading dislocation (TD) density and a precisely controlled carrier concentration can occur. Some promising growth methods for FS-GaN include hydride vapor phase epitaxy (HVPE), [3][4][5] ammonothermal growth, 6,7 and the Na-flux method. 8 Dislocations are a major type of crystallographic defect in GaN and are generally classified into basal plane dislocations (BPDs) within the {0001} planes or TDs that propagate approximately along the direction.…”

Revelation of Dislocations in β‐Ga2O3 Substrates Grown by Edge‐Defined Film‐Fed Growth

“…It has been well known that dislocations cause leakage current and premature breakdown. They might also act as nucleation sites for other types of defects that degrade devices, such as stacking faults . Dislocation density in most recent commercial EFG substrates is in the range of 10 3 –10 5 cm −2 .…”