Dresden 2011 – scientific programme
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O: Fachverband Oberflächenphysik
O 80: Epitaxy and growth: Metals and semiconductors I
O 80.5: Talk
Thursday, March 17, 2011, 16:00–16:15, WIL C307
Initial stages of the ion-beam assisted epitaxial GaN film growth on 6H-SiC(0001) — •Lena Neumann1, Jürgen Gerlach1, Thomas Höche1, and Bernd Rauschenbach1, 2 — 1Leibniz Institute of Surface Modification (IOM), D-04318 Leipzig, Germany — 2University Leipzig, Institute of Experimental Physics II, D-04103 Leipzig, Germany
The influence of the nitrogen ion-to-gallium atom flux ratio (I/A ratio) on the early stages of gallium nitride (GaN) nucleation and thin film growth directly on super-polished 6H-SiC(0001) substrates is studied. Ultrathin GaN films below 15 nm were formed using the ion-beam assisted molecular-beam epitaxy (IBA-MBE) technique. The deposition process was performed at a constant substrate temperature by evaporation of gallium using a conventional effusion cell and irradiation with hyperthermal nitrogen ions from a constricted glow-discharge ion source. The nitrogen ion flux was kept constant and the selection of different I/A flux ratios was done by varying the Ga flux. The GaN growth was determined by in situ reflection high energy electron diffraction and scanning tunneling microscopy measurements. The film microstructure was investigated by transmission electron microscopy. A strong dependence of the resulting film morphology and topography as a function of the Ga deposition rate could be observed. A three-dimensional island growth mode is favoured at I/A ratio >1. At higher Ga deposition rates (I/A ratio <1) the formation of islands developed through early coalescence into two-dimensional growth with the coalescence thickness being about 12 to 30 monolayers of GaN.