We perform fundamental studies of surface, ultrathin film, interface and nanostructure systems of relevance to advanced technology. Past studies have included research on atomic and molecular adsorption and reaction, thin film growth, and catalysis. Over the past decade our work has mainly involved basic and applied research into new inorganic and organic materials for nanoelectronics. Current interests also include alternative energy materials (for photovoltaics, catalysis, and energy storage), nanowires, graphene, MEMS, bio-materials interfaces, sensors, and nanotoxicity. Our group uses ion scattering, electron spectroscopy, scanning probe and electron microscopies, and other surface and nanoscience methods.
CMOS nanoelectronics (next generation transistors)
New materials: The semiconductor industry critically needs new materials and structures to continue scaling transistors. Our research in this area is directed at understanding and controlling the atomic scale properties of future generation of MOS (metal-oxide-semiconductor) gate stacks (the core region of a transistor). This work involves a range of new materials for metal gate electrodes (with appropriate work functions), dielectrics (with a higher dielectric constant than HfO2), and semiconductors (including Ge and GaAs-based channels). Key factors in choosing alternative materials for MOS gate stacks are that the structure, once grown, should display a high capacitance and high on-off ratio, have a low concentration of electrical defects, be thermally stable, and be manufacturable in appropriate structures. Our research on dielectrics has focused on studies of high permittivity oxides of Zr, Hf, La, Ti and Al. Growth studies using atomic layer deposition have been critical in learning how to engineer ultrathin films. An important aspect of our work is to develop an understanding of (and correlation between) the structural, compositional and electrical properties of relevant materials and structures. In addition to dielectrics, develop the basic scientific and conceptual tools, physical characterization methods, growth methods, and work function engineering strategies to enable optimal metal electrodes to be realized in device application. In addition to new materials, we also examine novel structures, including nanowire-based devices.
Key collaborators in this work are Torgny Gustafsson, Bob Bartynski, Len Feldman and members of the SRC and Sematech communities.
Organic materials for electronics and photonics
Organic materials have begun to replace inorganics and a few advanced device applications, and there is hope that with appropriate R&D effort, much greater impact for organics is forthcoming. We work on a variety of device-related projects that involve studies of polymers, small organic molecules, organic crystals, and graphene. Our work focuses primarily on surface and interface science of these materials. The applications of our work range from photovoltaics (OPV) to lighting and display (OLED) to electronics (OFET). Recent polymer work has focused mainly on hybrid organic-inorganic photovoltaics with one project using electropolymerization to integrate polythiophenes with ZnO nanowires. Single crystal organic work has focused on understanding the surface chemistry of rubrene. Graphene work has concentrated on exfoliation chemistries, functionalization, and characterization. Past work involved a precise characterization of molecule-electrode and electrode-molecule-electrode systems for molecular electronics. In most cases, once bonding and structure at the surfaces and interfaces are well understood, we work on fundamental measurements of electrical transport or optical absorption/emission. As with our inorganic work, we use an appropriate range of powerful surface and thin film methods to help develop a full understanding of the system under investigation.
Collaborators in these projects include Manish Chhowalla, Vitaly Podzorov, Huixin He, Eva Andrei and Yicheng Lu.
Other projects include basic studies of:
- Atomic layer deposition
- Cluster-based methods of ultrathin film growth (with CSMC)
- Ionic liquid surfaces and interfaces
- SiO2/SiC interfaces
- Nanowire growth and applications
- Electrodes for photonic and electronic devices
- Publications can be found at Garfunkel group main site.