Molten Barium Hydroxide as Defect Selective Drop Etchant for Dislocation Analysis on Aluminum Nitride Layers
L. Matiwe1, C. Hartmann1, L. Cancellara1, M. Bickermann1, A. Klump1, J. Wollweber1, S. Hagedorn2, M. Weyers2, and T. Straubinger1
Published in:
phys. stat. sol. (a), vol. 219, no. 7, pp. 2100707, doi:10.1002/pssa.202100707 (2022).
Abstract:
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°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.
1 Leibniz-Institut für Kristallzüchtung (IKZ), Max-Born-Straße 2, D-12489 Berlin, Germany
2 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, D-12489 Berlin, Germany
Keywords:
AlN crystals, barium hydroxide, defect etching
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