Linköping University (LiU), Sweden

LiU has a historic profile as an interdisciplinary environment that strives to integrate education and research, as well as bridging the gap between knowledge generated in research and practice. Materials science is a top research priority at LiU, with grants totaling >190MSEK/yr, and strongly supported by industry and institutes. It is extremely productive as judged by both academic and societal metrics. A hallmark of LiUs materials research program is its focus, and worldwide leadership, in the development of a very broad assembly of interlaced synthetic routes for the growth of materials with selected properties. Included are several novel approaches for self-organized 0, 1, 2, and 3 dimensional materials growth. LiU team has twenty years of experience with silicon carbide growth, and ten years of experience in carbon based films. In 1998 the group conducted the first growth of SiC in microgravity on the sounding rocket MASER 7 using a liquid phase epitaxial process. The group developed a PVT process for SiC substrates, and later an epitaxial growth process for thick layers (FSGP – Fast Sublimation Growth Process) with high growth rate. Already in 2002 LiU developed a process for formation of high quality ordered graphitic layers on the Si-face of a SiC substrate. The process was modified to produce monolayer graphene on SiC.

The graphene growth process by solid state decomposition is very complex and dynamic. Our experience from SiC has led to a deeper understanding of the surface reactions in development of well-controlled routes for growth of carbon based films.

Role in NANO-RF:

Wafer scale epitaxial graphene on SiC.

Laboratory resources:

The resources available for the group include: a sublimation growth furnace for wafers up to 50 mm in diameter, and all prerequisites for epitaxial graphene growth on SiC by thermal decomposition of the substrate material. To trace the impact of the starting surfaces on graphene quality, surface morphology of both SiC substrates and the subsequently grown graphene will be examined by atomic force microscopy (AFM) in different modes, Kelvin probe measurements, XPS and THz ellipsometry. All mentioned techniques are available in house. This will facilitate a well-organized feed back loop: growth/characterization- growth, and will allow the correct tuning of the growth conditions towards an optimal process for the carbon based films.

Key personnel:

Rositza Yakimova is professor in material science, Linköping University, in the field of semiconductor physics and technology. She has 35 years of experience in growth of semiconductor materials, such as SiC,AlN, etc. She is an internationally recognized expert in this field and she has been invited to several universities to share her competence. Since 1993 she has had a leading role in the development of the sublimation growth process of SiC crystals at LiU. The first SiC sublimation growth reactors in Sweden were designed with her essential contribution in collaboration with Epigress. During 1995-1999 she was employed by the company Okmetic, which preceded Norstel. In the recent years she participated in a technology transfer, as a consultant of Aixtron (former Epigress). She has pioneered research and delivered excellent results in AlN crystal growth and fabrication of large area homogeneous graphene and single crystal graphite on SiC.

Mikael Syväjärvi received his MSc degree in Applied Physics and Electrical Engineering 1995 and PhD in Materials Science 1999. He has expertise in liquid phase epitaxy, seeded sublimation bulk growth and sublimation epitaxy of SiC since 1995, as well as sublimation growth of AlN and preparation of high quality epitaxial graphitic layers (which have a quality that compares quite well with natural single crystals) and graphene. He was technically responsible for the experimental preparation for the successful launch in 1996 of the first growth of SiC in microgravity on the sounding rocket MASER 7 (the module is exposed at the museum of the Natural Science in Stockholm). Awarded twice with the young scientist award at the International Conference of Crystal Growth (1998 in Israel and 2001 in Japan). He is an original member of the entrepreneurial group PEAK at Linköping University and was selected for the Mentor 4 Research program. His research areas are graphene, and fluorescent SiC for LEDs and solar cells.

Tihomir Iakimov got his PhD from the Electrotechnical University of St. Petersburg, Russia in 1973. He has many years of experience in material synthesis such as sputtering deposition of nanostructured ceramics, crystal growth of silicon carbide and crystal machining of SiC (slicing and polishing). Since 1996 he has been involved in the LiU project on sublimation growth of SiC crystals and graphite formation on SiC. He proposed a design of a crucible for epitaxial growth of graphite on SiC, which under further elaboration of the process, is also used to fabricate large area epitaxial graphene on SiC. Since 1998 he has been the main responsible for the development of SiC slicing and polishing first at Okmetic AB and later at Norstel AB. He has an excellent expertise in the process engineering demanded for machining of crystal with high hardness. Dr. Iakimov has an inventive thinking favorably combined with precise process handling, which is a result of a high level of scientific knowledge and practical skills in the field.