Analysis of reaction between c+a and -c+a dislocations in GaN layer grown on 4-inch Si(111) substrate with AlGaN/AlN strained layer superlattice by transmission electron microscopy

Abstract

The behavior of dislocations in a GaN layer grown on a 4-inch Si(111) substrate with an AlGaN/AlN strained layer superlattice using horizontal metal-organic chemical vapor deposition was observed by transmission electron microscopy. Cross-sectional observation indicated that a drastic decrease in the dislocation density occurred in the GaN layer. The reaction of a dislocation (b=1/3[-211-3]) and anothor dislocation (b =1/3[-2113]) to form one dislocation (b =2/3[-2110]) in the GaN layer was clarified by plan-view observation using weak-beam dark-field and large-angle convergent-beam diffraction methods.

Observation of dislocations in β-Ga2O3 single-crystal substrates by synchrotron X-ray topography, chemical etching, and transmission electron microscopy

“…As a result, simultaneous equations could not be established to obtain b uvw . In contrast to our previous LACBED observation of 4H-SiC 56) and GaN, 60) it was difficult to obtain clear nodes in β-Ga 2 O 3 . The main reason for this might be related to the monoclinic structure, as its low symmetry gave rise to a large number of weak reflection lines that blurred the strong ones.…”

“…Next, we examined whether LACBED is capable of identifying the Burgers vectors of dislocations in β-Ga 2 O 3 . This TEM characterization technique was developed for the analysis of dislocations in Si and other single-crystal materials, [52][53][54][55] and has recently been applied to 4H-SiC [56][57][58][59] and GaN 36,60,61) for an accurate evaluation of dislocation Burgers vectors including their direction and magnitude. In the case of β-Ga 2 O 3 , when a dislocation with a Burgers vector of b uvw is made to overlap with a Laue reflection line of the reciprocal lattice vector of g hkl , theoretically we can expect the Laue reflection line to split into n nodes, where n = g hkl •b uvw (inner product) is satisfied.…”

Structural characterization of defects in EFG- and HVPE-grown β-Ga2O3 crystals

“…They also performed large-angle convergentbeam diffraction (LACBED), which enables precise determination of the Burgers vectors. [67][68][69] However, Yao et al also failed to determine the precise Burgers vector owing to the existence of complex factors disturbing the patterns, such as the highly dense network of higher-order Laue reflection lines. 66 types of dislocations were identified by TEM.…”

The dissociation of (a+c) misfit dislocations at the InGaN/GaN interface

“…Many theoretical and experimental works have dealt with the subject of the dissociation mechanism and glide of (a+c) dislocations in materials with hexagonal structure. [2][3][4][5][6] In the case of nitride semiconductors crystallising in the wurtzite structure, the (a+c) dislocations are frequently found in layers deposited on highly mismatched substrates, such as GaN or AlN on sapphire or silicon, 7,8 and their origin is probably due to the coalescence of slightly misoriented islands at early stages of an epilayer growth. 9 They also play an important role in the strain relaxation of nitride semiconductor layers crystallising in the wurtzite structure and oriented along [0001] direction.…”