Interface Chemistry for Nanoscale Devices

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Technical: The objectives of this project are (i) to determine the changes in interface electronic structure and properties as one scales from planar to nanowire geometries for organic and inorganic materials bound to Ge, and (ii) to examine, more generally, the impact of surface/interface chemical modification on hybrid heterostructure device properties, using both planar and nanowire configurations. The goal is to develop the conceptual tools, synthetic methodologies, and engineering strategies needed to design and chemically modify interfaces central to multi-component nanoscale devices. The research will concentrate on atomic and monolayer scale 'band alignment' as device geometries scale from planar to nanowire. The research will address key interface issues that must be understood when these materials are combined in nanoscale heterostructures. Studies will examine interfacial interactions of Ge with organic and inorganic layers in both nanowire and planar structures. The project will explore modification of the interfaces to: i) control oxidation, ii) passivate surface and interface defects, iii) tune band alignment (work function engineering), and iv) bond chemical species to interfaces for specific functionality. Expected outcomes include: A determination of the atomic and electronic structure of nanoscale interfaces; the establishment of an understanding of how chemistry and electronic structure differ between nanowire interfaces and their conventional planar analogues; and development of tools to control the electronic structure of interfaces and the resultant device properties by atomic and molecular modification/functionalization. High-resolution characterization tools that will be employed include surface, thin film, and nanoscale variants of: (i) photoemission and inverse photoemission spectroscopy, (ii) high resolution ion scattering, (iii) scanning probe microscopy, iv) electron microscopy (with energy loss spectroscopy), (v) optical spectroscopy, and (vi) electronic transport. Bilayer, multilayer and simple prototype devices will be examined. Results will be characterized in terms of current understanding of interface control, thus elucidating the important variables of size and dimensionality of the material constituents. Non-technical: The project addresses basic research issues in a topical area of materials science with technological relevance in electronics and photonics. Research findings are expected to impact a range of technological applications including CMOS nanoelectronics, photovoltaics, organic electronics, and chemical/biochemical sensors. A solid fundamental understanding of interfacial materials chemistry and physics of ultrathin films and nanowires is expected. The materials being explored offer low-cost and/or higher performance alternatives to traditional devices. A strong set of educational activities include: (i) the development of new courses in energy materials with a focus on interfaces, (ii) the expansion of Rutgers student internships and industrial exchanges, (iii) the development of a new set of interactions between Rutgers and African institutions (facilitated in part by a new NSF-IGERT), and (iv) the development of nano and surface science oriented educational modules. The modules will target middle school students and teachers, coupling with the Liberty Science Center and the Rutgers Math-Science Learning Center. Outreach will also emphasize the mentoring of women and underrepresented minorities.