Potential of Graphene as a Universal Substrate for Disruptive Epitaxial Devices

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Graphene's two dimensional (2D) carbon structure uniquely combines mechanical flexibility, weak surface bonding and a hexagonal lattice. When semiconductor crystals are grown onto graphene, its 2D sheet is expected to elastically reshape to accommodate crystal or thermal mismatches, enabling growth of high-quality semiconductors on arbitrary substrates, without crystal deformations and impairments. This is currently the subject of intense research in the community, but the question remains open as no viable solution was reached yet. Many of the observed effects during the initial phase of the crystal growth on graphene are surprising and still not fully understood. High performance semiconductor devices are made by growing special, thin, high quality “epitaxy” layers onto compatible substrates. However the substrates are costly and come from limited global resources, which often limit the possibility of integrating materials with complementary properties. In today's market, the performance expectations are reaching unprecedented levels that force the industry to design and produce devices based on stack of radically different crystal structures, a condition traditionally forbidden in epitaxy. The science and technology necessary to face this challenge remains to be fully developed, and the creation of new kinds of substrates, with the ability to accommodate these extreme conditions is a promising avenue. However, since these special substrates drive up device cost and limits its functionalities, any solution that might have hope to access the market must be cost-effective and scalable. This challenge motivated the question: “Is graphene the ultimate material to solve fundamental challenges of mismatched epitaxy?” My research program will bring together a multifaceted, high potential material (graphene) with a fundamental industrial and scientific challenge, to generate impact. I will specifically address the two main issues in III-V growth on graphene through original and innovative approache: engineer graphene's surface energy to enhance the nucleation of III-Vs materials on graphene through a nucleation process that I name “Anchor Point Nucleation”. This will involve students and researchers in work illuminating the physics of nucleation and growth for 3D crystals (GaAs, InP, GaN) onto 2D crystals (i.e: graphene). The potential here is vast, offering epitaxy and transfer of semiconductors onto arbitrary substrates (e.g: metals, ceramics, flexible polymers) for new generations of hybrid devices such as low-weight, flexible high-efficiency solar cells, and integration of III-V devices on Si, enabling compatibility with high speed electronics and photonics. A focus of the activity will be outcomes involving practical demonstrations on high-efficiency solar cells.