Epitaxial multilayers as substrates for the large area growth of graphene: Metal/YSZ/Si(111) and Diamond/Ir/YSZ/Si(111)

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The project explores concepts to synthesize graphene in a controlled way on substrates that offer a high potential for an up-scaling to wafer dimensions. The key component for the experiments are single crystal metal films grown via yttria-stabilized zirconia (YSZ) buffer layers on Si(111). Metals of the platinum group (Ir, Rh, Ru) are excellent substrates for growth of graphene by chemical vapor deposition (CVD). Ni, Cu, and CuxNiy offer the additional advantage that they can be etched by mild reagents that leave the graphene intact. As a second topic the sp3-sp2 conversion of (111) oriented diamond films grown epitaxially on Ir/YSZ/Si(111) as a means to generate epitaxial graphene will be studied.One focus of the work is the synthesis of the required twin-free metal films in single crystal quality with minimum mosaic spread and with low surface roughness on 4-inch Si wafers. Multilayer structures like Ir/YSZ/Si can easily sustain high temperatures above 1000°C in the CVD process. For metals like Cu, which are preferable for transfer concepts, strategies will be explored to increase the thermal stability, preventing delamination at high temperatures which allow deposition of high quality graphene. CVD growth of graphene on the metal films will be studied in Augsburg and in cooperation with various project partners. As an extension to the previous plans it is intended to prepare also off-axis metal and diamond layers. Their self-organized step structure could help to induce a lateral patterning of the graphene layers.For the transfer from the metallic growth surface to a dielectric support three different concepts will be investigated which comprise chemical as well as ion etching techniques and mechanical removal. Micro-Raman spectroscopy and LEED will be applied to assess the structural quality of the transferred films. The results of the growth studies will be transferred to a new CVD setup that allows processing of complete metal/YSZ/Si(111) wafers.