As the nanometer-scale features of IC chips become ever smaller, manufacturers are increasingly vexed by problems of overheating, electrical impedance, and noise—problems they’ve overcome in larger ICs. Researchers realize that it will take a multidisciplinary approach, with advances needed not only in semiconductors but also in photonics and biology to make the tinier, more energy-efficient versions that researchers envision. The steps to be taken to move recent breakthroughs in nanoelectronics from the lab to off-the-shelf products will be covered in dozens of presentations at the IEEE International Nanoelectronics Conference, to be held from 3 to 8 January 2010 in Hong Kong.
One subject that already has a significant amount of buzz in the nanoelectronics community is plasmonics, which refers to devices powered by the interaction of light with a piece of metal bonded to a dielectric material. When photons strike the metal, free electrons near the junction of the metal and insulator are excited but are restricted in their movements. The electrons, forced into lockstep, form a coherent wave at an optical frequency that can be amplified and converted into laser light.
Why is this important? Optical data transfer, using optical fibers, provides higher speed and bandwidth than electronic data signals, but the fiber bundles or reflective tubes required are bulkier than the tiny wires sufficient for data transfer using electrons. With data transferred by electrons at optical frequencies on the surface of metal wires, plasmonics delivers the best of optical and electronic data transfer with the drawbacks of neither. It is being developed for a number of applications, including its use in conventional silicon chips to speed up intrachip communication.
These applications herald the arrival of optical computing chips that operate at blazing speeds without generating the heat, noise, and other drawbacks that threaten to stall further miniaturization and performance improvements in microprocessors.
Harvard University researchers working out the fundamentals of lasers on chips are developing surface plasmon resonance lasers they say will some day make conventional optical components such as lenses unnecessary. Plasmonic waves interfere with the beams that emerge from a semiconductor laser in a way that makes them all run parallel to each other. The size- and cost-reducing result could be steerable laser beams with no moving parts.
The aim, says IEEE Member Nanfang Yu, a Harvard postdoctoral fellow and the lead author of a paper to be presented on plasmonic semiconductor lasers, is to put these lasers “on chips so optical communication, with photons as the power source and the medium for relaying signals, can be easily achieved.” By “easily achieved,” Yu means that applications—including so-called laser antennas, which improve the spatial resolution of microscopes by focusing the beam spot down to a size that is an order of magnitude smaller than the wavelength of the laser light—could be feasible in the next 10 to 15 years.
Senior Member Edward T. Yu, a professor of electrical and computer engineering at the University of Texas at Austin (and no relation to Nanfang Yu), will discuss how integrating plasmonic nanostructures with semiconductors will improve the performance of photovoltaic panels by making them better able to convert the energy in sunlight to electricity. These nanostructures will also make it possible to use photolithography to imprint IC features that are tens of nanometers wide even though the light beamed through the pattern mask during manufacture is of a wavelength that would previously not allow for features narrower than a few hundred nanometers.
Other topics to be discussed at the conference include the application of scanning tunneling microscopy to better understand how to control the molecular orientation and structures of self-assembled monolayers; learning from nature about how the structure of biological materials provides characteristics such as stiffness and flaw tolerance; and heat-transport phenomena in carbon nanofibers and nanotubes.
In addition to the presentations, the conference will offer nanofabrication workshops. And a special symposium on China’s contributions to nanoscience and nanotechnology will see researchers from the Chinese Academy of Sciences and the Chinese Academy of Engineering, both in Beijing, and Academia Sinica in Taipei, Taiwan, describe their work.
The event, to be held on the campus of the City University of Hong Kong, is sponsored by the IEEE Electron Devices Society.