Misfit relaxation of the(0001) interface
- 29 October 2001
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 64 (19), 195329
- https://doi.org/10.1103/physrevb.64.195329
Abstract
The epitaxial interface formed by a thin buffer layer of AlN deposited by molecular beam epitaxy on (0001) is investigated using electron microscopy techniques. Plan-view observations display a two-dimensional translational moiré pattern resulting from the difference in lattice parameters between the two crystals. The effective misfit of suggests the presence of a network of misfit interfacial dislocations. These are, most of the time, introduced every 8 atomic planes of the AlN lattice or 9 atomic planes of the lattice, which is directly verified by cross-section high-resolution electron microscopy (HREM). The density of threading dislocations terminating at the buffer/substrate interface is in agreement with the density of threading dislocations near the surface of the GaN film. This in conjunction with terminating fringes observed in the moiré patterns provides strong evidence that threading dislocations are connected with the interfacial misfit dislocations. Plan-view HREM images reveal that a threading dislocation is directly related to two extra prismatic AlN half-planes, the missing parts of which are associated with two misfit dislocations in the interfacial network. The Burgers vector of the threading dislocation equals the sum of the Burgers vectors of the two misfit dislocations and therefore is of the a type. Although misfit dislocations relax the larger fraction of the misfit strain, the AlN buffer layer is still under a compressive residual strain since the effective misfit is smaller than the natural misfit between the two lattices.
Keywords
This publication has 12 references indexed in Scilit:
- Lattice images of dislocations with edge components in GaN epilayers grown on Al2O3 substratesJournal of Crystal Growth, 2000
- Do we really understand dislocations in semiconductors?Materials Science and Engineering B, 2000
- Investigation of the atomic structure of the pure edge and a+c threading dislocations in gan layers grown by MBEMaterials Science and Engineering B, 1999
- Relaxation of Misfit-Induced Strain in Semiconductor HeterostructuresPhysica Status Solidi (a), 1999
- Dislocation generation in GaN heteroepitaxyJournal of Crystal Growth, 1998
- Direct observation of the core structures of threading dislocations in GaNApplied Physics Letters, 1998
- Quantitative Transmission Electron Microscopy Investigation of the Relaxation by Misfit Dislocations Confined at the Interface of GaN/Al2O3(0001)Japanese Journal of Applied Physics, 1998
- Characterisation of dislocations, nanopipes and inversion domains in GaN by transmission electron microscopyMaterials Science and Engineering B, 1997
- Defect structure of metal-organic chemical vapor deposition-grown epitaxial (0001) GaN/Al2O3Journal of Applied Physics, 1996
- Growth defects in GaN films on sapphire: The probable origin of threading dislocationsJournal of Materials Research, 1996