Nucleation and core-shell formation mechanism of self-induced InxAl1−xN core-shell nanorods grown on sapphire substrates by magnetron sputter epitaxy. (September 2016)

• Record Type: Journal Article
• Authors: Hsiao, Ching-Lien; Palisaitis, Justinas; Persson, Per O.Å.; Junaid, Muhammad; Serban, Elena Alexandra; Sandström, Per; Hultman, Lars; Birch, Jens
• Is Part Of: Vacuum. Volume 131(2016)
• Page Start: 39
• Page End: 43
• Publication Date: 2016-09
• Subjects: InAlN -- Nanorods -- Nanostructures -- STEM -- EDX -- Sputtering -- MSE; Vacuum -- Periodicals; 621.55
• DOI: 10.1016/j.vacuum.2016.05.022
• Languages: English
• ISSNs: 0042-207X

Abstract

Abstract: Nucleation of self-induced Inx Al1−x N nanorod and core-shell structure formation by surface-induced phase separation have been studied at the initial growth stage. The growth of well-separated core-shell nanorods is only found in a transition temperature region (600 °C ≤ T ≤ 800 °C) in contrast to the result of thin film growth outside this region (T < 600 °C or T > 800 °C). Formation of multiple compositional domains, due to phase separation, after ∼20 nm Inx Al1−x N epilayer growth from sapphire substrate promotes the core-shell nanorod growth, showing a modified Stranski-Krastanov growth mode. The use of VN seed layer makes the initial growth of the nanorods directly at the substrate interface, revealing a Volmer-Weber growth mode. Different compositional domains are found on VN template surface to support that the phase separation takes place at the initial nucleation process and forms by a self-patterning effect. The nanorods were grown from In-rich domains and initiated the formation of core-shell nanorods due to spinodal decomposition of the Inx Al1−x N alloy with a composition in the miscibility gap. Highlights: A comprehensive study on the structural evolution of Inx Al1−x N nanorods and thin films grown by magnetron sputter epitaxy. The formation mechanism of self-induced core-shell Inx Al1−x N nanorod structure is reported. The morphological and compositional evolutions of ternary alloys upon temperature and seed layer are reported. Two different growth modes, Stranski-Krastanov and Volmer-Weber, are proposed.