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DS: Fachverband Dünne Schichten

DS 13: Poster Session III: Layer properties: electrical, optical and mechanical properties; Thin film characterization: structure analysis and composition (XRD, TEM; XPS, SIMS, RBS..)

DS 13.16: Poster

Montag, 11. März 2013, 17:00–20:00, Poster B1

Microstructural investigation of epitaxial grown GaN thin films using hyperthermal ions — •David Poppitz, Andriy Lotnyk, Jürgen W. Gerlach, and Bernd Rauschenbach — Leibniz-Institut für Oberflächenmodifizierung e. V., Permoserstr. 15, D-04318 Leipzig

Gallium nitride thin films grown with ion beam assisted molecular beam epitaxy on different substrates and at different growth parameters are studied by using (S)TEM imaging and chemical analysis. The aim of this study is to get information about the interface between gallium nitride film and the substrate materials using high resolution TEM. The gallium nitride thin films were grown on 6H-SiC(0001) and Al2O3(0001) substrates without using buffer layers. The influence of the substrate temperature in the range from 630 °C to 750 °C and the nitrogen ion/gallium flux ratio on the growth process is investigated. The aim was to examine the defect structure of the films with a high resolution Cs-corrected analytical TEM. To get high resolution pictures sensitive and sophisticated preparation methods were used and optimized relating to the material system. TEM lamellae were sliced by using focused ion beam technique and afterwards the samples were thinned by ultra-low energy argon ion polishing. In this process amorphous layers and gallium implementations from the cutting process with high energetic gallium ions were removed. Very thin sample thicknesses of a few nanometers have been achieved and high resolution (S)TEM images could be taken. Further chemical analysis at the nanometer scale by using EDX- and EELS- measurements were done.