Dr. Gerko Oskam

CINVESTAV-IPN, Unidad Mérida Km 6 Antigua Carretera a Progreso 
Apartado Postal 73 Cordemex 97310. Mérida, Yuc., México 
Tel: +52 (999) 1242129 Fax: +52(999)942 94 38 
E-mail: oskam@mda.cinvestav.mx
Categoría: Investigador titular CINVESTAV 3-A


ESCOLARIDAD
Doctorado en Ciencias, (Química), febrero 1993
Tésis: “The Electrochemical Properties of Metallized III-V Semiconductors” Vakgroep Gecondenseerde Materie, Debye Instituut, Universiteit Utrecht, HOLANDA

Maestria en Ciencias (Química), enero 1989
Tésis: “The reduction of Br2 at GaAs electrodes” Universiteit Utrecht, Utrecht, HOLANDA

EXPERIENCIA PROFESIONAL
Investigador CINVESTAV 3-A, Departamento de Física Aplicada, CINVESTAV-Mérida. A partir de 2001.
Associate Research Scientist, 1996 - 2001
Dept. of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, USA
Post-doctorate Associate, 1993 - 1996
Dept. of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, USA

DISTINCIONES
Nivel II del Sistema Nacional de Investigadores
Visiting Associate Professor, 2001 - present
Dept. of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, USA

RESUMEN DE PRODUCTIVIDAD
Publicaciones con arbitraje: 40
Capítulos de libros: 2
Artículos de revisión: 1
Patentes (USA): 2
Memorias in extenso (congresos internacionales): 16
Citations: > 700


LINEAS DE INVESTIGACION
Semiconductor electrochemistry
Fabrication and characterization of porous and nanostructured materials
Ordered assembly of nanoparticles
Electrochemical deposition of metals
Energy technology and solar energy conversion


1. Synthesis of metal oxide nanoparticles
The electrical and optical properties of metal oxide particles such as TiO2, ZnO, and SnO2 are a strong function of their composition, size, and surface chemistry, however, surprisingly little is known about the nucleation and growth kinetics of nanoparticles. Hence, there is a need for a fundamental understanding of the formation mechanisms of nanoparticles, and the effect of the processing parameters on their properties. In this project, we investigate the relationship between the structure and the properties of metal oxide nanoparticles fabricated by solution phase methods.

2. Electrical properties of ordered assemblies of nanoparticles
The access to well-defined metal oxide nanoparticle colloids as described in the first project provides an opportunity to investigate the ordered assembly of nanocrystalline particles in 1D, 2D, or 3D lattices. The aim of this project is to find innovative ways to form ordered assemblies of nano-particles and to determine their electrical and optical properties. Assembly by deposition of particles in a template is an attractive method as the template material, form, and size can be changed to the desired assembly of nanoparticles. For example, electrophoretic deposition can be utilized to prepare 1D chains of nanoparticles by using a porous membrane such as polycarbonate, alumina, or mica. The pore sizes in these materials can range from 10 – 200 nm. The resulting 1D particle chains are ideal for the determination of the charge transport properties by varying the number of particle-particle contacts. Templating can also be applied for the formation of ordered 3D structures. The most successful method is to use latex or silica spheres with sizes ranging from 50 nm to 100 µm. The polystyrene spheres can be assembled in an ordered 3D structure. By using different templates, the influence of the particle size on the electrical transport properties can be determined.

3. Dye-sensitized solar cells
In 1991, O’Regan and Grätzel reported a dye-sensitized TiO2 photoelectrochemical cell with a solar energy conversion efficiency of close to 10%, sparking a renewed interest in efficient photoelectrochemical cells based on inexpensive oxide materials and a simple fabrication process. Improvements of the cell performance and operating life are essential for the implementation of these new solar cells. Crucial aspects include improvement of the electrical properties of the metal oxide nanoparticulate thin films. The aim of this project is to optimize the TiO2 thin films, and to evaluate the use of metal oxides other than TiO2, mixtures of oxide particles, and core-shell metal oxide nanoparticles for application in photoelectrochemical cells.

4. Electrochemical deposition of thin films on electronic materials
The goal of this project is the electrochemical deposition of thin, continuous metal films onto semiconductors (SiC, GaN) and electronic barrier materials (TiN, TaN, Ta). The initial stages of nucleation and growth determine the microstructure of the final film and, thus, have a large effect on the electrical properties such as the resistivity and the electromigration resistance. For instance, electrochemical copper deposition was introduced by IBM in 1997 for the metallization in chips: in order to obtain high quality copper films, however, a copper seed layer has to be evaporated onto the TiN diffusion barrier prior to electrodeposition. Knowledge of the relationships between the nucleation and growth mechanisms, the microstructure of thin films, and the electrical properties is critical for the implementation of electrochemical deposition methods in the fabrication of integrated circuits.


CAPITULOS EN LIBROS, ARTICULOS DE REVISION
3. “Dye-sensitized, nanostructured metal oxide photoelectrodes for solar energy conversion” G. Oskam, in: Current Topics in Electrochemistry, Vol. 10, pp. 141-162, Research Trends, 2004.

2. “Semiconductor-Electrolyte Interfaces” G. Oskam, P. M. Hoffmann, A. Natarajan, P. C. Searson, in: Wiley Encyclopedia of Electrical and Electronics Engineering, John G. Webster (Ed.), Vol. 19, pp. 29-43, Wiley&Sons, New York, 1999.

1. “Electrochemical deposition of metals on silicon” - review article G. Oskam, J. G. Long, A. Natarajan, P. C. Searson, J. Phys. D.; Appl. Phys., 31, 1927-1949 (1998).


PATENTES
2. “Method for Making Carbon / Ceramic Composite Electrodes for Charge Storage Units” G. Oskam, P. C. Searson, US Patent No. 6,019,803 (Feb. 1, 2000).

1. “Copper metallization structure and method of construction” G. Oskam, P. C. Searson, P. M. Vereecken, J. G. Long, P. M . Hoffmann, US Patent No. 6,309,969 (Oct. 30, 2001).


PUBLICACIONES
40. “The influence of the reactant concentrations on the synthesis of ZnO nanoparticles” Z. Hu, J. F. Herrera Santos, G. Oskam, and P. C. Searson, J. Colloid Interface Sci. 288, 313-316 (2005).

39. “The synthesis of ZnO nanoparticles in 2-propanol by reaction with water” Z. Hu, D. J. Escamilla Ramírez, B. E. Heredia Cervera, G. Oskam, and P. C. Searson, J. Phys. Chem. B, 109, 11209-11214 (2005).

38. “Dye-sensitized SnO2 electrodes with iodide and pseudohalide redox mediators” B. V. Bergeron, A. Marton, G. Oskam, and G. J. Meyer, J. Phys. Chem. B, 109, 973-943 (2005).

37. “Influence of oxide thickness on nucleation and growth of copper on tantalum” A. Radisic, G. Oskam, and P. C. Searson, J. Electrochem. Soc., 151, C369-C374 (2004).

36. “The influence of solvent on the growth of ZnO nanoparticles” Z. Hu, G. Oskam, and P. C. Searson, J. Colloid Interface Sci., 263, 454-460 (2003).

35. “Deposition of AuxAg1-x/AuyAg1-y Multilayers and Multisegment Nanowires” C. Ji, G. Oskam, Ding, Y., Erlebacher, J. D., Wagner, A. J., and P. C. Searson, J. Electrochem. Soc., 150, C523-C528 (2003).

34. “Electrodeposition of Ni/SiC contacts” G. Oskam, P. J. Patel, J. G. Long, and P. C. Searson, J. Appl. Phys., 93, 10104-10109 (2003).

33. “The influence of anion on the coarsening kinetics of ZnO nanoparticles” Z. Hu, G. Oskam, R. L. Penn, N. Pesika, and P. C. Searson, J. Phys. Chem. B, 107, 3124-3130 (2003).

32. “The growth kinetics of TiO2 nanoparticles from Titanium(IV) alkoxide at high water/Titanium ratio” G. Oskam, A. Nellore, R. L. Penn, and P. C. Searson, J. Phys. Chem. B, 107, 1734-1738 (2003).

31. “Coarsening of metal oxide nanoparticles” G. Oskam, Z. Hu, R. L. Penn, N. Pesika, and P. C. Searson, Phys. Rev. E, 66, 011403 (2002).

30. “Epitaxial assembly in aged colloids” R. L. Penn, G. Oskam, P. C. Searson, A. Stone, D. R. Veblen, J. Phys. Chem. B, 105, 2177 (2001).

29. “Pseudo-halogens for dye-sensitized TiO2 photoelectrochemical cells” G. Oskam, B. Bergeron, G. J. Meyer, and P. C. Searson, J. Phys. Chem. B, 105, 6867 (2001).

28. “Electrochemical Nucleation and Growth of Copper on Si(111)” C. Ji, G. Oskam, and P. C. Searson, Surf. Sci., 492, 115-124 (2001)..

27. “Electrodeposition of Copper on Silicon from Sulfate Solution” C. Ji, G. Oskam, and P. C. Searson, J. Electrochem. Soc., 148, C746 (2001).

26. “Electrochemical nucleation and growth of gold on silicon (100) surfaces” G. Oskam and P. C. Searson, Surf. Sci., 446, 103 (2000).

25. “Fabrication of n-type 4H-SiC/Ni junctions using electrochemical deposition” G. Oskam, M. W. Cole, and P. C. Searson, Appl. Phys. Lett, 67, 1300 (2000).

24. “Electrochemistry of gold deposition on n-Si(100)” G. Oskam and P. C. Searson, J. Electrochem. Soc., 147, 2199 (2000).

23. “Electrochemical deposition of copper on n-Si/TiN” G. Oskam, P. M. Vereecken, and P. C. Searson, J. Electrochem. Soc., 146, 1436 (1999).

22. “Sol-gel synthesis of carbon / silica gel electrodes for lithium intercalation” G. Oskam and P. C. Searson, Electrochem. and Solid-State Lett., 2, 610 (1999).

21. “Electrochemical fabrication of n-Si/Au Schottky junctions” G. Oskam, D. van Heerden, and P. C. Searson, Appl. Phys. Lett., 73, 3241 (1998).

20. “Characterization of silicon surfaces in HF solution using microwave reflectivity” A. Natarajan, G. Oskam, and P. C. Searson, J. Appl. Phys., 83, 2112 (1998).

19. “Analysis of the impedance response due to surface states at the semiconductor / solution interface” P. M. Hoffmann, G. Oskam, and P. C. Searson, J. Appl. Phys., 83, 4309 (1998).

18. “Synthesis and characterization of carbon / ceramic composite electrodes” G. Oskam and P. C. Searson, J. Phys. Chem., J. Phys. Chem. B, 102, 2464 (1998).

17. “The potential distribution at the semiconductor / solution interface” A. Natarajan, G. Oskam, and P. C. Searson, J. Phys. Chem., B. 102, 7793 (1998).

16. “Porous GaAs and porous silicon: a comparison” F. M. Ross, G. Oskam, P. C. Searson, J. M. Macaulay, J. A. Liddle, Phil. Mag. A., 75, 525 (1997).

15. “The formation of porous GaAs in HF solutions” G. Oskam, A. Natarajan, P. C. Searson, and F. M. Ross, Appl. Surf. Sci., 119, 160 (1997).

14. “Energetics and kinetics of surface states at n-type Si surfaces in aqueous fluoride solutions” G. Oskam, P. M. Hoffmann, J. C. Schmidt, and P. C. Searson, J. Phys. Chem.-US, 100, 1801 (1996).

13. “In situ measurements of interface states at silicon surfaces in fluoride solutions” G. Oskam, P. M. Hoffmann, and P. C. Searson, Phys. Rev. Lett., 76, 1521 (1996).

12. “Electrical properties of n-type (111) Si in aqueous K4Fe(CN)6 solution. Part 1: Surface state and recombination impedance measurements” G. Oskam, J. C. Schmidt, P. M. Hoffmann, P. C. Searson, J. Electrochem. Soc., 143, 2531 (1996).

11. “Electrical properties of n-type (111) Si in aqueous K4Fe(CN)6 solution. Part 2: Intensity modulated photocurrent spectroscopy” G. Oskam, J. C. Schmidt, and P. C. Searson, J. Electrochem. Soc., 143, 2538 (1996).

10. “Electron transport in porous nanocrystalline TiO2 photoelectrochemical cells” F. Cao, G. Oskam, G. J. Meyer, and P. C. Searson, J. Phys. Chem.-US, 100, 17021 (1996).

9. “Electrical and optical properties of porous nanocrystalline TiO2 films” F. Cao, G. Oskam, P. C. Searson, J. M. Stipkala, T. A. Heimer, F. Farzad and G. J. Meyer, J. Phys. Chem - US., 99, 11974 (1995).

8. “A solid state, dye sensitized photoelectrochemical cell” F. Cao, G. Oskam, and P. C. Searson, J. Phys. Chem.-US, 99, 17072 (1995).

7. “The influence of electrodeposited gold on the properties of III-V semiconductor electrodes. Part 1: Results of current-potential measurements on p-GaAs” G. Oskam, D. Vanmaekelbergh, and J. J. Kelly, Electrochim. Acta, 38, 291 (1993).

6. “The influence of electrodeposited gold on the properties of III-V semiconductor electrodes. Part 2: A study of the impedance due to gold-related surface states at p-GaAs electrodes” G. Oskam, D. Vanmaekelbergh, and J. J. Kelly, Electrochim. Acta, 38, 301 (1993).

5. “The influence of electrodeposited gold on the properties of III-V semiconductor electrodes. Part 3: Results on n-GaAs electrodes provided with thick gold layers” G. Oskam, D. Vanmaekelbergh, and J. J. Kelly, Electrochim. Acta, 38, 1115 (1993).

4. “The electrical and electrochemical properties of gold-plated InP” G. Oskam, L. Bart, D. Vanmaekelbergh, and J. J. Kelly, J. Appl. Phys., 74, 3238 (1993).

3. “The electrochemistry of InP in aqueous K3Cr(CN)6 solution” G. Oskam and E. A. Meulenkamp, J. Electroanal. Chem., 326, 213 (1992).

2. “A reappraisal of the frequency dependence of the impedance of semiconductor electrodes” G. Oskam, D. Vanmaekelbergh, and J. J. Kelly, J. Electroanal. Chem., 315, 65 (1991).

1. “Current-doubling, chemical etching and the mechanism of two-electron reduction reactions at GaAs. Part 1: Experimental results for H2O2 and Br2” B. P. Minks, G. Oskam, D. Vanmaekelbergh, and J. J. Kelly, J. Electroanal. Chem., 273, 119 (1989) .

Última ActualizaciÓn: Septiembre 14, 2006