Stress evolution in thick GaN layers grown by HVPE

•Full process time in-situ curvature measurements during HVPE growth.•Rough estimation of the growth strain from the in-situ bow.•Validation of increasing tensile growth strain during high temperature HVPE growth.•Inclination of threading dislocations can be a root cause of the growth strain.•The gr...

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Bibliographic Details
Published in:Journal of crystal growth 2020-11, Vol.550, p.125887, Article 125887
Main Authors: Lukin, G., Meissner, E., Friedrich, J., Habel, F., Leibiger, G.
Format: Article
Language:English
Subjects:
A1. Dislocations
A1. Lattice bow
A1. Stresses
A3. Hydride vapor phase epitaxy
B1. Gallium nitride
Crystal defects
Epitaxial growth
Evolution
Gallium nitrides
Point defects
Residual stress
Strain
Substrates
Thickness measurement
Threading dislocations
Vapor phase epitaxy
Vapor phases
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Summary:•Full process time in-situ curvature measurements during HVPE growth.•Rough estimation of the growth strain from the in-situ bow.•Validation of increasing tensile growth strain during high temperature HVPE growth.•Inclination of threading dislocations can be a root cause of the growth strain.•The growth of crack free 3-in. HVPE GaN crystals is demonstrated. This paper investigates the evolution of internal stress in thick GaN layers grown by Hydride Vapor Phase Epitaxy (HVPE) in terms of related strain and bow of the stack GaN layer – substrate. The long-time in-situ thickness and bow measurements were performed during the growth of 3 in. HVPE crystals by using a novel interferometric curvature measurement system. Based on the analysis of the obtained in-situ bow curves, using an elastic model of a two layer system, the presence of an intrinsic negative (tensile) growth strain increasing with the layers thickness could be proven. The inclination of threading dislocations is shown to be a possible root cause for the increasing growth strain. In contrary, the impact of the incorporation of point defects on the lattice deformation is assumed to play a minor role for the appearance of tensile growth strain, at least for typical impurity concentrations in the HVPE environment.
ISSN:0022-0248
1873-5002
DOI:10.1016/j.jcrysgro.2020.125887