Assistant Professor of Materials Science and Engineering
Ph.D. Materials Science, FOM Institute, Amsterdam, The Netherlands(1998)
M.S. Physics, Eindhoven University of Technology, Eindhoven, The Netherlands (1994)
McCullough Bldg., Room 349
(650) 736-2152
Email: brongersma@stanford.edu
Website: http://www.stanford.edu/group/BrongersmaGroup/

Research Interests

• Nanoscale electronic and photonic materials and devices
• Guiding and manipulation of light in metal-optic structures
• Optical properties of semiconductor nanocrystals
• Optical sensors for bio-applications
• Fundamentals of ion beam modification of materials

Projects

The research in our group is focused on the fabrication and characterization of nanometer-size electronic and optical devices. The ability to engineer materials at the atomic level has opened a myriad of possibilities for the advancement of technologies that impact the areas of semiconductors, telecommunications, chemistry, and biology.

For future developments in nano-technology, it is essential to provide communication channels that allow controlled information and energy transport at the nanometer level. The design of a dense network of electronic interconnects that can link together gigantic numbers of nanoscale devices on a chip is not a trivial task. Reduction in the pitch and cross-section of metallic interconnects gives rise to local heating and an increase in the RC time constant (delay) of interconnected structures. Optical interconnects do not exhibit such problems. Moreover, optical interconnects have a much higher information carrying capacity because of the higher operating frequency. Unfortunately, conventional optical interconnects do not scale down well. The reduction in size of dielectric optical components is fundamentally limited by the diffraction limit of light, imposing a lower size limit on a guided light mode of about ??/2n (about 0.5 ??m). This is true even for all dielectric photonic crystal structures. Providing a mechanism that allows optical interconnection with individual nano-devices beyond the limits set by diffraction would tremendously expand the information processing capabilities of nanoscale structures. This however, will require a new class of materials and nanostructures.

In our group we are investigating the optical properties of metallic nanostructures. Such structures exploit the unique properties of plasmon excitations (see Fig. 1) on metallic surfaces to provide the possibility of confining, transmitting and manipulating light at a length scale that is far smaller than the wavelength of the incident photons.

Fig. 1. Schematic representation of an electron density wave propagating along a metal/dielectric interface. The charge density oscillations and associated electromagnetic fields are called surface plasmon-polariton waves. The exponential dependence of the electromagnetic field intensity on the distance away from the interface is shown on the right. These waves can be excited very efficiently with light in the visible range of the electromagnetic spectrum.

Presently, we are using metallic nanostructures to fabricate/analyze:

• Sub-diffraction limit optical waveguides based on metallic nanoparticle arrays and nanowires.
• Plasmon excitations on thin films with ordered arrays of holes.
• Ultra-sensitive optical sensors for biological applications.
• Electronic interconnects.

Selected Publications

2002

Observation of near-field coupling in metal nanoparticle chains using far-field polarization spectroscopy, S.A. Maier, M.L. Brongersma, P.G. Kik, and H.A. Atwater, Phys. Rev. B 65, 193408 (2002).

2001

"Plasmonics - A Route to Nanoscale Optical Devices," S.A. Maier, M.L. Brongersma, P.G. Kik, S. Meltzer, A.A.G. Requicha, and H.A. Atwater, Adv. Mater. 13, 1501 (2001).

"Models for quantitative charge imaging by atomic force microscopy," E.A. Boer. L.D. Bell. M.L. Brongersma, H.A. Atwater, J. Appl. Phys. 90, 2764 (2001).

"Synthesis and characterization of aerosol silicon nanocrystal nonvolatile floating-gate memory devices," M.L. Ostraat, J.W. De Blauwe, M.L. Green, L.D. Bell, M.L. Brongersma, J. Casperson, R.C. Flagan, H.A. Atwater, Appl. Phys. Lett. 79, 433 (2001).

"Manipulation and Charging of Single Si Nanocrystals by Atomic Force Microscopy," E.A. Boer, L.D. Bell, D.H. Santamore, M.L. Brongersma, and H.A. Atwater, Appl. Phys. Lett. 78, 3133 (2001).

"Localized Charge Injection in SiO2 Films Containing Silicon Nanocrystals," E.A. Boer, M.L. Brongersma, L.D. Bell, and H.A. Atwater, Appl. Phys. Lett. 79, 791 (2001).

"Colloidal Assemblies Modified by Ion Irradiation," E. Snoeks, A. van Blaaderen, T. van Dillen, C.M. Kats, K. Velikov, M.L. Brongersma, and A. Polman, Nucl. Instr. and Meth. B. 178, 62 (2001).

2000

"Electromagnetic Energy Transfer and Switching in Nanoparticle Chain-arrays Below the Diffraction Limit," M.L. Brongersma, J. Hartman, and H.A. Atwater, Phys. Rev. B 62, R16356, (2000).

"Electromagnetic Energy Transport Along Arrays of Closely Spaced Metal Rods as an Analogue to Plasmonic Devices," S.A. Maier, M.L. Brongersma, and H.A. Atwater, Appl. Phys. Lett. 78, 16 (2000).

"Monodisperse Silica and ZnS Particles with Continuously Variable Shape Made by Ion Irradiation of Micro-Spheres," E. Snoeks, A. van Blaaderen, T. van Dillen, C.M. Kats, K. Velikov, M.L. Brongersma, and A. Polman, Advanced Materials 12, 1511 (2000).

"Origin of MeV Ion Irradiation-Induced Stress Changes in SiO2," M.L. Brongersma, E. Snoeks, T. van Dillen, and A. Polman, J. Appl. Phys. 88, 59 (2000).

"Formation Mechanism of Silver Nanocrystals Made by Ion Irradiation of Na+/Ag+ Ion-Exchanged Sodalime Silicate Glass," D.P. Peters, C. Strohhofer, M.L. Brongersma, J. van der Elsken, and A. Polman. Nucl. Intrum. Methods Phys. B 168, 237 (2000).

"Strong Exciton-Erbium Coupling in Si Nanocrystal-Doped SiO2," P.G. Kik, M.L. Brongersma, and A. Polman, Appl. Phys. Lett. 76, 2325 (2000).

"Size-Dependent Electron-Hole Exchange Interaction in Si Nanocrystals," M.L. Brongersma, P.G. Kik, A. Polman, K.S. Min, and H.A. Atwater, Appl. Phys. 76, 351 (2000).