TEM analysis of threading dislocations in crack‐free Al _x Ga _{1− x} N grown on an AlN(0001) template

Uniform growth of GaN on AlN templated (111)Si substrate by HVPE

“…We have many dark spots, of which density is decreased by increasing the AlN thickness. Since the dark spots have close connection to the dislocations, we may conclude that the density of dislocation is reduced by thick AlN intermediate layer [10]. On the basis of the results shown above, we tried to improve the surface morphology to ride off the 'flower' completely.…”

Simulation supported analysis of the effect of SiNxinterlayers in AlGaN on the dislocation density reduction

“…As group-III nitride wafers are still not available in sufficient amount and quality, AlN has to be grown on foreign substrates such as Al 2 O 3 (sapphire). Unfortunately the large lattice mismatch between the AlGaN/Al 2 O 3 interface of up to -14% leads to the formation of strain induced misfit dislocations at the interface, which are the cause of the generation of threading dislocations (TD), inducing a high dislocation density in the range of 10 10 cm -2 and decreasing the crystal quality [1,2]. As published among others in [3,4], a promising possibility to reduce the dislocation density at the surface of an AlGaN layer system is the growth of intermediate SiN x layers.…”

Evidence for moving of threading dislocations during the VPE growth in GaN thin layers

“…The reduction is achieved by the formation of half loops (or hairpins) of TDs. The mechanism of reduction is explained as follows [1,4]. Since AlN has a smaller lattice dimension than GaN, interfacial dislocations of a-type are generated and an individual of the interfacial dislocations is converted to be a pair of TDs in the AlGaN layer, as shown in Fig.…”