Reduction of the dislocation density in HVPE-grown GaN epi-layers by an in situ SiNx treatment

Structural evolution of GaN layers grown on (0001) sapphire by hydride vapor phase epitaxy

“…This selective process accounts for the morphology evolution that we observed ( Fig. 5(a)-(d)) and that has been reported in the early stage of GaN overgrowth [19,27,28]. Because these islands align perfectly with sapphire, and thus perfectly with each other, dislocations are not required at coalescence boundaries.…”

Growth evolution of SixNy on the GaN underlayer and its effects on GaN-on-Si (111) heteroepitaxial quality

“…Due to only a slight difference in the FWHM value of the GaN(002) plane between 663 and 719 arcsec by modifying the t g of Si x N y , the change in the FWHM value of the GaN(102) plane is more important to evaluate than the epilayer quality of regrowth GaN. For the t g of Si x N y at 0, 5,10,15,20,25,30 and 60 s, the FWHM values of the GaN(102) plane were 1589, 1348, 1327, 1259, 1169, 971, 636 and 681 arcsec, respectively. As known to all, the XRD curve of the GaN(002) plane is sensitive to the screw-and mixed-types of TDs.…”

Defect-rich GaN interlayer facilitating the annihilation of threading dislocations in polar GaN crystals grown on (0001)-oriented sapphire substrates

“…This interlayer forces the TDs to bend in the vicinity of the interface between the interlayer and the underlying GaN and consequently helps to reduce their density. Other approaches reducing the TD density are the deposition of a SiN x mask that terminates the propagation of TDs into the upper GaN layer 18,19 and the use of AlN nucleation layers on (0001)-oriented sapphire substrates that modifies the lattice mismatch between the substrate and GaN. [20][21][22] In a recent publication, Stanchu et al described the positive effect of compositionally graded AlGaN buried layers in GaN/AlGaN/GaN stacks on the lattice strain relaxation and on the annihilation of TDs.…”