Berlin 2015 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 19: Ion and electron beam induced processes

DS 19.8: Vortrag

Mittwoch, 18. März 2015, 11:45–12:00, H 2032

Epitaxial GaN films deposited on ion-beam structured Si(111) with SiN_x intermediate layer — •Annemarie Finzel, Jürgen W. Gerlach, Frank Frost, Renate Fechner, Marc Teichmann, Andriy Lotnyk, and Bernd Rauschenbach — Leibniz-Institut für Oberflächenmodifizierung e.V. (IOM Leipzig), Permoserstraße 15, D-04318 Leipzig, Germany

In this study, Si(111) substrates were structured by using a Kr ion beam in order to obtain nanometric ripple or terrace-like surface structures. After cleaning and oxide etching, the pristine as well as the ion-beam structured substrates were irradiated with hyperthermal nitrogen ions (E_kin ≤ 25 eV) at elevated temperatures to create a thin SiN_x intermediate layer for preventing melt-back etching of the Si substrate surface by Ga. Immediately afterwards, thin GaN films were deposited on these pre-treated substrates by ion-beam assisted molecular-beam epitaxy (IBA-MBE). The characterization of the samples by (S)TEM and AFM shows that the 1-2 nm thin SiN_x intermediate layer is sufficient to protect the Si from melt-back etching. Although the layer is partially amorphous, it is possible to grow GaN films epitaxially on the SiN_x layer (FWHM of the c-plane XRD rocking curve: 2^∘). Furthermore, the findings reveal on the one hand a higher wettability of the ion-beam structured Si substrates, leading to more compact and dense films in comparison the non-structured ones. On the other hand, the GaN films deposited on the structured Si substrates exhibit a higher mosaicity (FWHM of the XRD rocking curves: 2.8-3.0^∘). The results will be discussed.