Electronic Cloth and Other Novelties

Each year, a variety of emerging technologies are unveiled at the International Electron Devices Meeting (IEDM), and this year is no exception. Following are a few highlights selected from abstracts provided by conference organizers. The conference will be held Dec. 8-10 at the Hilton Washington and Towers.

University of California-Berkeley researchers will discuss how they built plastic pentacene transistors directly on cloth fibers, an industry first. The researchers say "e-textiles" may be used to embed sensing, actuation and displays into clothing and surface coverings.

In a process that is compatible with textile manufacturing, the transistors were fabricated using a 125 µm diameter aluminum wire as the gate line. In practice, this wire may be directly woven into an e-textile to serve as a gate interconnect. Interestingly, the transistors were fabricated without conventional lithography. Instead, the researchers made use of the natural pattern of textiles, accomplishing patterning via shadowing from over-woven fibers. The fiber was masked with orthogonal over-woven 50 µm diameter wires (Figure ). These served as channel masks; a transistor was formed at every intersection. 100 nm gold was evaporated to form source/drain contacts.

In e-textile research at Berkeley, transistors were patterned via shadowing from over-woven fibers. The fiber was masked with orthogonal over-woven 50 µm diameter wires. (Source: University of California-Berkeley)

A long-time industry goal is to fabricate high-performance silicon TFTs on transparent plastic substrates. The problem in doing so has always been that the high processing temperatures needed to make the TFTs would melt the plastic. A team from Seoul National University will describe how they made silicon TFTs on plastic at an acceptable 150°C processing temperature, using excimer laser annealing and a special inductively coupled plasma vapor deposition process. The TFTs exhibited extremely high electron mobilities (141 cm²/V-sec).

For the first time, researchers fabricated a large-area pressure-sensor matrix on a flexible plastic sheet, integrating high-quality organic transistors and rubbery pressure sensors. The sheet may be wrapped around a robotic arm or other shapes to produce a sense of touch. The pressure sensors are made from conductive rubbery sheets sandwiched between two 100 µm-wide metal lines crossing at right angles. One of the lines is connected to an organic transistor; the other to ground. The transistor's drain current changes as a function of applied pressure to the sensor.

Harvard University's Charles Lieber, the 2001 Feynman Prize winner for his pioneering work in nanowires, will present a paper titled, "Nanowires as Building Blocks for Nanoelectronics and Nanophotonics." Nanowires can be made from different materials, and are so small (5-10 nm diameters) they have quantum properties. Lieber will review a general framework for the growth of single-crystal nanowires, and will discuss their electrical transport properties and heterostructures. He'll describe nanotechnology-enabled applications like ultrasensitive chemical and biological sensors, along with the fundamental optical and optoelectronic properties of compound semiconductor nanowires and nanowire heterostructures. The discussion will include approaches for preparing multicolor crossed nanowire light-emitting diodes (LEDs), arrays of multicolor LEDs, optically pumped nanowire lasers and electrically driven nanowire injection lasers.

Spintronics is the name given to the emerging discipline of manipulating the "spins" of atoms and electrons. A University of California-Santa Barbara researcher will discuss recent experiments that investigate the electronic, photonic and magnetic manipulation of electron and nuclear spins in a variety of semiconductor structures. He will focus on the underlying physics for quantum information processing in the solid state.

For additional information on emerging technologies, go to www.semiconductor.net/emerging.