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Research Interests and Selected Publications

Optical Metrology

Device Physics & Nanotechnology

Current research concerns optical metrology of solids, especially based on ellipsometric principles, and device issues typically concentrating upon nanotechnology requirements.

Optical metrology:

We have built a spectroscopic ellipsometer operating from 5 eV to 9 eV, and used this to study the optical properties of bulk materials and thin films relevant to device technology. A major emphasis has been on high-k gate dielectrics. We are developing a scanning probe ellipsometer capable of 1 nm lateral resolution.

 Recent publications in this area

 Measurement of the band offsets between amorphous LaAlO3 and silicon, L. F. Edge and D. G. Schloma), S. A. Chambers, E. Cicerrella and J. L. Freeoufb),  B. Holländer and J. Schubert, Applied Physics Letters 84, 726 (2004).

Separate and Independent Control of Interfacial Band Alignments and Dielectric Constants in Transition Metal Rare Earth Complex Oxides, G. Lucovsky, Y. Zhang, J. L. Whitten, D. G. Schlom, and J. L. Freeouf, Microelectronic Engineering 72, 288 (2004).

 ¡°Optical Properties of La-Based High-K Dielectric Films,¡± E. Cicerrella, J.L. Freeouf, L.F. Edge and D.G. Schlom, T. Heeg, J. Schubert, and S.A. Chambers, Journal of Vacuum Science and Technology A.  23, 1676 (2005).

 ¡°Spectroscopic studies of the electrical structure of transition metal and rare earth complex oxides,¡± Lucovsky, G., Zhang, Yu; Whitten, J.L.; Schlom, D.G.; Freeouf, J.L. Physica E: Low-Dimensional Systems and Nanostructures, 21, 712-716 (2004).

¡°Rare-earth scandate single- and multi-layer thin films as alternative gate oxides for microelectronic applications,¡± Heeg, T.; Wagner, M.; Schubert, J.; Buchal, Ch.; Boese, M.; Luysberg, M.; Cicerrella, E.; Freeouf, J.L.,  Microelectronic Engineering, 80, n SUPPL., Jun 17, 2005, (14th Biennial Conference on Insulating Films on Semiconductors,)  p 150-153 (2005).

¡°Growth and Properties of Epitaxial Rare-Earth Scandate Thin Films," by T. Heeg, J. Schubert, C. Buchal, E. Cicerrella, J.L. Freeouf, W. Tian, Y. Jia, and D.G Schlom,  Applied Physics A. 83, 103 (2006).

Dielectric and Optical Properties of Epitaxial Rare-Earth Scandate Films and Their Crystallization Behavior, H. M. Christen, G. E. Jellison, Jr., I. Ohkubo, S. Huang, M. E. Reeves, E. Cicerrella, J. L.             Freeouf, Y. Jia, and D. G. Schlom, Applied Physics Letters  88, 262906 (2006). 

Device Physics and Nanotechnology:

Current efforts have concentrated upon properties of semiconductor nanowires and solar cell design. Contact issues have been a major emphasis and will be again.

Selected publications in these areas


Ideal Schottky Diodes on Passivated Silicon, M. Wittmer and J. L. Freeouf, Phys. Rev Lett. 69, 2701 (1992).

Schottky Barriers: An Effective Workfunction Model, J. L. Freeouf and J. M. Woodall,  Appl. Phys. Lett. 39, 727 (1981).

¡°Effective" Barrier Heights of Mixed Phase Contacts: Size Effects, J. L. Freeouf, T. N. Jackson, S. E. Laux, and J. M. Woodall, Appl. Phys. Lett. 40, 634 (1982).

Effect of Interfacial Hydrogen in CoSi2/Si(100) Schottky Barrier Contacts, M. O. Aboelfotoh, A. D. Marwick, J. L. Freeouf, Phys. Rev. B49, 10753 (1994).

Microscopic Compound Formation at the Pd‑Si (111) Interface, J. L. Freeouf, G. W. Rubloff, P. S. Ho, and T. S. Kuan, Phys. Rev. Letters 43, 1836 (1979).


Solar Cells:

 Radiation hard and gravimetric efficient thin film InP solar cells,  Sun Yanning, Woodall, J.M., Freeouf, J.L. and Walters, R.J., Proceeding of the 29th  Photovoltaic Specialists Conference, p.994 ¨C997 (2002).

Double Graded, Drift Dominated InP Solar Cells, Yanning Sun, Jerry M. Woodall, Jeffrey H. Warner, Robert J. Walters,  John L. Freeouf, Aristo Yulius, and Guohua Li, 3rd World Conference on Photovoltaic Energy Conversion, Osaka, Japan, May 12-16,  2003, Proceedings of the 3rd World Conference on Photovoltaic Energy Conversion, 726 (2003).

¡°Extreme radiation hardness and light-weighted thin-film indium phosphide solar cell and its computer simulation,¡± Li, Guohua; Yang, Qingfen; Yan, Zonglin; Li, Wennian; Zhang, Shan; Freeouf, John; Woodall, Jerry M.,  Solar Energy Materials and Solar Cells  75,    307 (2003).



 Atomic Layer Deposition of ZnSe/CdSe Superlattice Nanowires, R. Solanki, J. Huo, J. L. Freeouf, and B. Miner,  Applied Physics Letters 81, 3864 (2002).

Directed growth of nickel silicide nanowires, C. A. Decker, R. Solanki,a)J. L. Freeouf, and J. R. Carruthers, D. R. Evans, Applied Physics Letters 84, 1389 (2004).

¡°Electroluminescence from silicon nanowires,¡± Huo, J. Solanki, R., Freeouf, J.L.; Carruthers, J.R., Nanotechnology  15, 1848 (2004).