TEM study of defect structure of GaN epitaxial films grown on GaN/Al2O3 substrates with buried column pattern

Effect of screw threading dislocations and inverse domain boundaries in GaN on the shape of reciprocal-space maps

“…In polar [001]-oriented GaN, the dominant microstructure defects are threading dislocations (TDs). Their density, which varies between 10 5 and 10 10 cm À2 (Hino et al, 2000;Motoki et al, 2002;Xu et al, 2002;Datta et al, 2004;Hertkorn et al, 2008;Booker et al, 2010;Mynbaeva et al, 2016), is one of the most important factors downgrading the electronic properties of GaN layers (Speck & Rosner, 1999). One of the common techniques used to detect TDs and quantify their density is X-ray diffraction (XRD).…”

Ta-Doped Ga2O3 Epitaxial Films on Porous p-GaN Substrates: Structure and Self-Powered Solar-Blind Photodetectors

“…Furthermore, the porous substrate can be used as a template for the epitaxial lateral overgrowth, resulting in the formation of stacking faults (SFs) in the lower part of the Ga 2 O 3 overgrowth layer. 21 The TDs formed during the initial growth of the film will bend and/or stop when passing through the SFs, leading to a decrease in the TD density in the subsequent growth film, as shown in Figure 5. 21−23 To investigate the in-plane epitaxial relationship between the film and substrate, the XRD φ-scans of the β-Ga 2 O 3 {4̅ 01} (χ = 23.44°) and GaN {101̅ 2} (χ = 39.10°) planes were applied to analyze the film deposited on the S 60 substrate.…”

“…The porous structures are formed by the decomposition of GaN molecules at the defects, , leading to a decrease in the defect density, so there are fewer threading dislocations (TDs) that continue into the Ga 2 O 3 film on the porous substrate compared with that on the nonporous substrate. Furthermore, the porous substrate can be used as a template for the epitaxial lateral overgrowth, resulting in the formation of stacking faults (SFs) in the lower part of the Ga 2 O 3 overgrowth layer . The TDs formed during the initial growth of the film will bend and/or stop when passing through the SFs, leading to a decrease in the TD density in the subsequent growth film, as shown in Figure . − …”

“…Furthermore, the porous substrate can be used as a template for the epitaxial lateral overgrowth, resulting in the formation of stacking faults (SFs) in the lower part of the Ga 2 O 3 overgrowth layer . The TDs formed during the initial growth of the film will bend and/or stop when passing through the SFs, leading to a decrease in the TD density in the subsequent growth film, as shown in Figure . − …”