Professor Yves J. Chabal

Research Activities


In our laboratory, we use (and in some cases develop) optical spectroscopic and imaging techniques to explore elementary processes at surfaces and interfaces of technologically important electronic, photonic, organic and more recently biological heterostructures. For instance, we have been leading the implementation of infrared absorption spectroscopy to develop a detailed mechanistic understanding of semiconductor surface cleaning (both by wet and dry techniques), passivation, and chemical functionalization. In particular, we have devised sensitive, in-situ methods to probe the interaction of chemical species and the formation of thin dielectric films in a variety of environments, including liquids, ultra-high vacuum (UHV), and gaseous ambients. We are also probing the interaction of hydrogen in a variety of environment, most recently in storage materials for the hydrogen fuel economy. The work in our group has a direct impact on:
  1. Microelectronics, by identifying the surface modification after various wet chemical processes (HF etching, acid/base cleaning and etching) for several types of semiconductors (groups IV, IV-IV, III-V), by characterizing the nature of H, Cl, OH and oxide passivation of semiconductor surfaces, and by uncovering the growth mechanism of high-k dielectrics on silicon. We are currently exploring the growth by Atomic Layer Deposition (ALD) of Al2O3 and HfO2 with sub nm equivalent oxide thickness (to replace SiO2) and the best wet chemical cleaning methods for high mobility substrates (e.g. Ge, InP) to replace silicon in future CMOS devices. We are also investigating elementary processes at the surface of SiC, an important substrate for high temperature, high speed, and high voltage electronics.
  2. Optoelectronics, by providing chemical information and badly needed fundamental understanding of III-V semiconductor surface passivation. After studying wet chemical etching and oxidation of InP, we are now exploring gaseous oxidation in controlled environments (e.g. UHV).
  3. H2 storage for hydrogen fuel economy, by examining the manner in which hydrogen molecules interact and get incorporated into complex metal hydrides and metal organic framework (MOF) materials. In the case of metal hydrides, we study the dissociation and subsequent adsorption of H2 on Ti-doped aluminum surfaces to better understand and control the formation of complex metal hydrides (e.g. NaAlH4). For the MOF materials, we focus on the weak interactions between H2 molecules and the metal and organic ligands to design more effective ways of increasing the hydrogen concentration.
  4. Organic electronics, by characterizing the chemical and structural nature of self-assembled monolayers (SAM's) on both metal and semiconductor surfaces. We are focusing on providing chemical and structural information to understand electronic conduction in organic materials by paying special attention to contact issues (substrate/SAM interfaces and effects of depositing top metal electrodes on SAM films). We are also developing spectroscopic methods to study the dependence of electronic conduction on conformational changes within the SAM's.
  5. Nanoelectronics, by using biological approaches to patterning surfaces on the nm and sub-nm scale. For instance, the possibility to manipulate DNA scaffolding is used to meet tight nanolithography requirements of integrated nano-circuits. An important aspect of this work is the control of DNA bonding to semiconductor surfaces. To this end, we are working on the fundamentals of DNA/surface interactions.
  6. Biosensors and biomedical applications, by understanding the interaction of biological macro-molecules (DNA, glucose, LDL, etc) with both organic and inorganic substrates. For instance, by studying the modulation of the electric field and charge transfer mechanisms by biological molecules, we are devising ways to implement electronic detection of biological species. The field of bio-sensors is wide open and in need of accurate surface characterization tools. Our group is therefore exploring the implementation of several tools specifically for biomedical applications, including spectroscopy and imaging. We are also exploring various means of single-wall carbon nanotube chemical functionalization to perform specific cellular functions both at the cell membrane and within the cell body.
Our group is interdisciplinary in nature, with collaborations in Physics, Chemistry, Materials Science, chemical and biomedical engineering, and even with collaboration with the Medical School. We have ongoing collaborations with National Laboratories (NIST, BNL, Sandia) and with laboratories in Belgium, France, Germany and Italy, and have access to the National Synchrotron Light Source at Brookhaven Laboratory. Our goal is to develop the synergy necessary for substantial scientific advances in surface and interfacial science, and to benefit in the process core US industries and national initiatives of the Department of Energy.


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