News

posted on 04 July 2008 08:19

University of Pennsylvania researchers have invented a nanowire technology that stores 3 bits of information in a nanowire unit leading to the prospect of denser computer memories.

As reported in Physorg.com the nanowires - (pictured left with core arrowed) extraordinarily thin wires on the molecular scale - have a sheath of germanium telluride (GeTe) wrapped around a core of a germanium/antimony/tellurium compound (Ge2Sb2Te5). Both these are phase change materials with a pulsed electrical charge heating them and changing their state from crystalline (ordered) to amorphous (disordered).

When both core and shell are crystalline their resistance is low; when both are amorphous their resistance is high, which equate to two values: 0; and 1. When the core is amorphous and the shell crystalline we have a third resistance level which corresponds to a third value of 2.

(If we have three values from a cell then bit aka 'binary digit' is the wrong term. We are dealing with trinary values perhaps and they should be called trits?)

The wires are apparently fairly simple to craft into structures with a self-assembly feature.

The research work is described in the June 13, 2008, online edition of Nano Letters  (ASAP Article, 10.1021/nl801482z). The actual research paper, Core−Shell Heterostructured Phase Change Nanowire Multistate Memory, is available to ACS Publications subscribers here.

Don't get too enthusiastic. This research is a decade or more away from actual products.

^{[Paul Roberts, news editor.]}