Atomic force microscopy of partially polished and epi-ready c-plane GaN substrates obtained by an ammonothermal method

In this paper, the propagation of scratches on the surfaces of c-plane GaN substrates due to slicing and polishing is studied through atomic force microscopy (AFM). For epi-ready substrates, the AFM images confirm a flat surface with atomic step roughness, while for partially polished GaN substrates...

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Bibliographic Details
Published in:Applied physics express 2014-05, Vol.7 (5), p.55504
Main Authors: Serafinczuk, Jaros aw, Jó wiak, Grzegorz, Pa etko, Piotr, Kudrawiec, Robert, Kucharski, Robert, Zajac, Marcin, Gotszalk, Teodor Pawe
Format: Article
Language:English
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Summary:In this paper, the propagation of scratches on the surfaces of c-plane GaN substrates due to slicing and polishing is studied through atomic force microscopy (AFM). For epi-ready substrates, the AFM images confirm a flat surface with atomic step roughness, while for partially polished GaN substrates, many scratches are visible in the AFM images. A Fourier analysis of the AFM images shows that the scratches propagate more easily along the {m-plane} and {a-plane} directions on a c-plane GaN surface. Most of these scratches are generated by the mechanical slicing of GaN crystals and/or non-optimal polishing conditions. A proper chemomechanical polishing process is able to remove the damaged material and obtain a flat surface with atomic step roughness. This observation is evidence for the anisotropy of mechanical properties of GaN crystals in the microscale range.
ISSN:1882-0778
1882-0786
DOI:10.7567/APEX.7.055504