16 February 2004 Improvement of nanostructured GaN films grown on sapphire by laser-induced reactive epitaxy
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Gallium nitride (GaN) thin films were grown by laser induced molecular beam epitaxy (LIMBE). Their microstructures were studied by transmission electron microscopy (TEM). Threading dislocations with Burgers vectors of 1/3<1120>, 1/3<1123> and [0001] were observed as common linear defects with predominantly the first type. Additionally, nano-structured planar defects as called domain boundaries were found. Convergent beam electron diffraction (CBED) technique coupled with chemical and cathodoluminescence measurements was employed to characterize the nano-structured domains, indicating that a domain is of Ga-polarity with respect to the adjacent matrix which is of N-polarity. It was found that experimental parameters such as N/Ga ratio were closely associated with the development of domains as well as the surface morphology. High-resolution transmission electron microscopy (HRTEM) results indicate that IDBs have Ga-N bonds between domains and the adjacent matrix without displacements along the c-axis in the basal planes. Upon the determination of the polar property of a thin GaN film and the optimization of experimental conditions, the nano-structured GaN films can be modified and controlled by changing substrate and pre-growing an AlGaN layer and a GaN buffer layer.
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H. Zhou, J. M. Bell, F. Phillipp, H. Schroeder, "Improvement of nanostructured GaN films grown on sapphire by laser-induced reactive epitaxy", Proc. SPIE 5648, Smart Materials III, (16 February 2004); doi: 10.1117/12.581385; https://doi.org/10.1117/12.581385

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