Molten Barium Hydroxide as Defect Selective Drop Etchant for Dislocation Analysis on Aluminum Nitride Layers

In this article, the suitability of the etchants NaOH/KOH and Ba(OH)2 for defect etching of metalorganic vapour‐phase epitaxy (MOVPE) grown AlN layers with a MgO‐assisted “drop method” is compared. Defect selectivity for the new etchant Ba(OH)2 is confirmed by the local TEM analysis. Temperature dep...

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Bibliographic Details
Published in:Physica status solidi. A, Applications and materials science Applications and materials science, 2022-04, Vol.219 (7), p.n/a
Main Authors: Matiwe, Lucinda, Hartmann, Carsten, Cancellara, Leonardo, Bickermann, Matthias, Klump, Andrew, Wollweber, Jürgen, Hagedorn, Sylvia, Weyers, Markus, Straubinger, Thomas
Format: Article
Language:English
Subjects:
AlN crystals
Aluminum
Atomic force microscopy
Barium hydroxide
defect etching
Epitaxial growth
Etch pits
Etchants
Etching
Low temperature
Magnesium oxide
Microscopy
Precipitates
Selectivity
Sodium hydroxide
Statistical methods
Temperature dependence
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Summary:In this article, the suitability of the etchants NaOH/KOH and Ba(OH)2 for defect etching of metalorganic vapour‐phase epitaxy (MOVPE) grown AlN layers with a MgO‐assisted “drop method” is compared. Defect selectivity for the new etchant Ba(OH)2 is confirmed by the local TEM analysis. Temperature dependence (420–500 °C) of etch pit sizes of a‐, mixed‐, and c‐type dislocations for both etchants are investigated by statistical evaluation of scanning electron microscopy (SEM) images. Additionally, the etch pit shape is analyzed for samples etched at 460 °C by atomic force microscopy (AFM) measurements. While a‐ and mixed‐type dislocations result in pits of comparable size and shape for both etchants, c‐type dislocations are already strongly etched with NaOH/KOH at low temperatures leading to over‐etching and MgO precipitation. Ba(OH)2, in contrast, generates smaller c‐type etch pits at low and medium etching temperatures and no MgO precipitates and is therefore preferable for drop etching. Ba(OH)2 is introduced as a superior etchant for defect etching of metalorganic vapour‐phase epitaxy (MOVPE) grown AlN layers with an MgO‐assisted “drop method”. Unlike the standard etching agent NaOH/KOH, there are no MgO precipitations present in the temperature range 400–500 °C and the dislocation types (a, c, mixed) are easily distinguishable.
ISSN:1862-6300
1862-6319
DOI:10.1002/pssa.202100707