The Surface and Microanalysis Science Division of CSTL performs research into new and improved measurements, standards, and instrumentation for optical characterization of thin films and interfaces. The emphasis is on in-situ characterisation of technically relevant system. Specific emaphsis is placed on the development of nonlinear optical (NLO) spectroscopies based on ultrafast lasers. This work is done in colloboration with the Laser Applications Group of the Optical Technology Division of PL. NLO spectroscopies have the traditional advantages of most optical techniques; they are nondestructive and can be deeply penetrating and are thus appropriate to in situ diagnostics. Additionally, NLO spectroscopies have unique advantages over linear spectroscopies for the study of buried interfaces. In centrosymmetric bulk media, second order mixing is symmetry forbidden, thus NLO techniques are specifically interface sensitive, where inversion symmetry is broken. Also, NLO techniques are more sensitive to interface structure by virtue of the transformation properties of the relevant mixing coefficients. The present NIST program is exploring the application of NLO spectroscopy with femtosecond lasers to characterization of the electronic structure of, and carrier dynamics at, interfaces critical to the semiconductor industry. In collaboration with the Biomaterials Group of CSTL, and the Electronics Applications Group in the Materials Science and Engineering Laboratory, vibrationally-resonant sum frequency generation is being developed for chemical characterization of interfaces relevant to catalysis, polymer and biosensor technologies.

Spectroscopic Characterization of Buried Metal/Molecule/Semiconductor Interfaces

In-Situ Ellipsometric Study of the Adsorption of Additives on Ru

Optical Characterization of Organic Electronic Thin Films

Characterization and Control of gel-fluid phase transitions in supported phospholipid monolayer films

Spectroscopic Study of the Structure of Oligo-phenylene-ethynlyene Monolayers with Molecular Electronics Implications

Selective study of molecular order at interfaces with vibrationally-resonant sum frequency generation via thin film interference effects

Complete List

Resources:

• Amplified femtosecond laser sources for generating tunable ultrafast pulses from about 10 microns in the IR to 200 nm in th UV.
• Spectrographs, polarizers and high sensitivity detectors (cooled PMTs and CCD arrays).
• Spectroscopic ellipsometer
• FTIR and UV-Vis spectrometers.
• Ultra-high vacuum systems for sample preparation and characterization.

CSTL Staff:

Competitive adsorption of PEG, Cl-, and SPS/MPS on Cu: An in situ ellipsometric study, M.L. Walker, L.J. Richter, T.P. Moffat
J. Electrochem Soc 153, C557-C561 (2006).

Electrical and spectroscopic characterization of metal/monolayer/Si devices, C.A. Richter, C.A. Hacker, L.J. Richter, J. Phys. Chem. B 109, 21836-21841 (2005).

The structure of polystyrene at the interface with various liquids, Clayton S.-C. Yang, Philip T. Wilson, Lee J. Richter, Macromolecules 37, 7742-7746 (2004)

Optical Characterization of Oligo(phenylene-ethynlyene) Molecular Electronic Switch Monolayers on Au, Lee J. Richter, Clayton S.-C. Yang, Philip T. Wilson, Christina A. Hacker, Roger D. van Zee, Joshua J. Stapleton, David L. Allara, Yuxing Yao, James M. Tour, J. Phys. Chem. B 108, 12547-12559 (2004).

Complete List