Mapping strain gradients in the FIB-structured InGaN/GaN multilayered films with 3D X-ray microbeam

This research presents a combined experimental-modeling study of lattice rotations and deviatoric strain gradients induced by focused-ion beam (FIB) milling in nitride heterostructures. 3D X-ray polychromatic microdiffraction (PXM) is used to map the local lattice orientation distribution in FIB-str...

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Bibliographic Details
Published in:Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2010-11, Vol.528 (1), p.52-57
Main Authors: Barabash, R.I., Gao, Y.F., Ice, G.E., Barabash, O.M., Chung, Jin-Seok, Liu, W., Kröger, R., Lohmeyer, H., Sebald, K., Gutowski, J., Böttcher, T., Hommel, D.
Format: Article
Language:English
Subjects:
Dislocations
Gallium nitrides
Indium gallium nitrides
Lattice rotations
Lattices
Microorganisms
Nitride semiconductors
Scanning electron microscopy
Simulation
Strain
Three dimensional
X-ray microbeam
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Summary:This research presents a combined experimental-modeling study of lattice rotations and deviatoric strain gradients induced by focused-ion beam (FIB) milling in nitride heterostructures. 3D X-ray polychromatic microdiffraction (PXM) is used to map the local lattice orientation distribution in FIB-structured areas. Results are discussed in connection with microphotoluminescence (μ-PL), fluorescent analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) data. It is demonstrated that FIB-milling causes both direct and indirect damage to the InGaN/GaN layers. In films subjected to direct ion beam impact, a narrow amorphidized top layer is formed. Near the milling area, FIB-induced stress relaxation and formation of complicated 3D strain fields are observed. The resulting lattice orientation changes are found to correlate with a decrease and/or loss of PL intensity, and agree well with finite element simulations of the three-dimensional strain fields near the relaxed trenches. Experimentally, it is found that the lattice surface normal has an in-plane rotation, which only appears in simulations when the GaN-substrate lattice mismatch annihilates the InGaN-substrate mismatch. This behavior further supports the notion that the film/substrate interface is incoherent.
ISSN:0921-5093
1873-4936
DOI:10.1016/j.msea.2010.04.045