Building on earlier work to grow nanowires horizontally on the surface of wafers (see “Gold Nano Anchors Put Nanowires in Their Place”), NIST researchers used conventional semiconductor manufacturing techniques to deposit small amounts of gold in precise locations on a sapphire wafer. In a high-temperature process, the gold deposits bead up into nanodroplets that act as nucleation points for crystals of zinc oxide, a semiconductor. A slight mismatch in the crystal structures of zinc oxide and sapphire induces the semiconductor to grow as a narrow nanowire in one particular direction across the wafer. Because the starting points and the growth direction are both well known, it is relatively straightforward to add electrical contacts and other features with additional lithography steps.
As proof of concept, the NIST researchers have used this procedure to create more than 600 nanowire-based transistors, a circuit element commonly used in digital memory chips, in a single process. In the prototype process, they report, the nanowires typical grew in small bunches of up to eight wires at a time, but finer control over the size of the initial gold deposits should make it possible to select the number of wires in each position. The technique, they say, should allow industrial-scale production of nanowire-based devices. ###
For more examples of NIST research on nanowire electronics, see: “New Design Developed for Silicon Nanowire Transistors,” “Growing Glowing Nanowires to Light Up the Nanoworld,” “New Fabrication Technique Yields Nanoscale UV LEDs,” “Placing Single Nanowires: NIST Makes the Connection,” and “Silicon Nanowires Upgrade Data-Storage Technology.” Links found at: nist.gov/techbeat/nanowire
* B. Nikoobakht. Toward industrial-scale fabrication of nanowire-based devices. Chem. Mater., ASAP Article 10.1021/cm071798p S0897-4756(07)01798-X. Web Release Date: October 9, 2007.
Contact: Michael Baum michael.baum@nist.gov, 301-975-2763, National Institute of Standards and Technology (NIST)
Technorati Tags: Nano or Nanotechnology and Nanotech and Nanowire Device Fabrication or National Institute of Standards and Technology and nanodroplets or Factor key to severity of community-associated methicillin-resistant staph infections identified and A Christmas Carol Charles Dickens and UD researchers race ahead with latest spintronics achievement
No comments:
Post a Comment