Origin of a-plane (Al,Ga)N formation on patterned c-plane AlN/sapphire templates
J. Phys.: Conf. Ser., vol. 471, no. 012038 (2013).
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a-plane (Al,Ga)N layers can be grown on patterned c-plane AlN/sapphire templates with a ridge direction along Al2O3. Scanning nanobeam diffraction reveals that the formation of a-plane layers can be explained by nucleation of c-plane (Al,Ga)N with (Al,Ga)N || Al2O3 at the ridge sidewalls. Faster growth of the top (1120)(Al,Ga)N facet in the vertical direction leads to the overgrowth of c-plane (Al,Ga)N nucleated on the horizontal ridge and trench surfaces. Phase separation into binary GaN and AlN takes place during the first growth stages. However, this fades out and does not influence the composition of the final thick a-plane (Al,Ga)N layer.
1 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, D-12489 Berlin, Germany
2 Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
81.05.Ea III-V semiconductors; 64.75.-g Phase equilibria; 81.15.Kk Vapor phase epitaxy; growth from vapor phase; 64.60.Q- Nucleation; 68.55.-a Thin film structure and morphology.