This book includes a plain text version that is designed for high accessibility. To use this version please follow this link.
50


nanotimes News in Brief


most promising terahertz technologies are based on small semiconductor transistor-like structures that are able to modulate a terahertz signal at room tem- perature, which is a significant advantage over ear- lier modulators that could only operate at extremely cold temperatures. Unfortunately, these transistor- like devices rely on a thin layer of metal called a “metal gate” to tune the terahertz signal. This metal gate significantly reduces the signal strength and limits how much the signal can be modulated to a lackluster 30%.


By replacing the metal gate with a single layer of graphene, the researchers have predicted that the modulation range can be significantly expanded to be in excess of 90%. This modulation is controlled by applying a voltage between the graphene and semiconductor. Unlike the metal gate modulator, the graphene design barely diminished the output power of the terahertz energy. Made up of a one- atom-thick sheet of carbon atoms, graphene boasts a host of amazing properties: it’s remarkably strong, a superb thermal insulator, a conductor of electrici- ty, and now a better means to modulate terahertz radiation.


Berardi Sensale-Rodriguez, Tian Fang, Rusen Yan, Mi- chelle M. Kelly, Debdeep Jena, Lei Liu, and Huili (Gra- ce) Xing: Unique prospects for graphene-based terahertz modulators, In: Applied Physics Letters, Vol. 99(2011), Article 113104 [3 pages], DOI:10.1063/1.3636435 http://dx.doi.org/10.1063/1.3636435


11-09 :: September 2011


Jin-Woo Han and Meyya Meyyappan at the Cen- ter for Nanotechnology at NASA Ames Research Center in Moffett Field, USA, have developed a new flexible memory fabric woven together from interlocking strands of copper and copper-oxide wires. At each juncture, or stitch along the fabric, a nanoscale dab of platinum is placed between the fibers. This “sandwich structure” at each crossing forms a resistive memory circuit. Resistive memory has received much attention due to the simplicity of its design.


© Meyya Meyyappan (ARC-T) / Jin-Woo Han (ARC-RD/USRA)


The copper-oxide fibers serve as the storage medi- um because they are able to change from an insula- tor to a conductor simply by applying a voltage.


The copper wires and the platinum layers serve as the bottom and top electrodes, respectively. This design easily lends itself to textiles because it natu- rally forms a crossbar memory structure where the fibers intersect.


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67