X-ray determination of threading dislocation densities in GaN/Al2O3(0001) films grown by metalorganic vapor phase epitaxy

Viktor S. Kopp (1) , Vladimir M. Kaganer (1) , Marina V. Baidakova (2) , Wsevolod V. Lundin (2) , Andrey E. Nikolaev (2) , Elena V. Verkhovtceva (2) , Maria A. Yagovkina (2) , Nikolay Cherkashin (3)

1 PDI - Paul-Drude-Institut für Festkörperelektronik
2 A.F. Ioffe Physical-Technical Institute
3 CEMES - Centre d'élaboration de matériaux et d'études structurales

Densities of a- and a+c-type threading dislocations for a series of GaN films grown in different modes by metalorganic vapor phase epitaxy are determined from the x-ray diffraction profiles in skew geometry. The reciprocal space maps are also studied. Theory of x-ray scattering from crystals with dislocations is extended in order to take into account contribution from both threading and misfit dislocations. The broadening of the reciprocal space maps along the surface normal and the rotation of the intensity distribution ellipse is attributed to misfit dislocations at the interface. We find that the presence of a sharp AlN/GaN interface leads to an ordering of misfit dislocations and reduces strain inhomogeneity in GaN films.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Viktor S. Kopp, Vladimir M. Kaganer, Marina V. Baidakova, Wsevolod V. Lundin, Andrey E. Nikolaev, et al.. X-ray determination of threading dislocation densities in GaN/Al2O3(0001) films grown by metalorganic vapor phase epitaxy. Journal of Applied Physics, 2014, 115 (7), pp.073507. ⟨10.1063/1.4865502⟩. ⟨hal-01721159⟩