Beyond 65 nm node, the ultra-narrow channel memory device serves as a possible technology for further scaling. A self-assembled carbon nanotube (CNT) channel with self aligned metal nanocrystals is proposed as an alternative to Si based ultra-narrow channel memory. The device demonstrates large memory window and single-electron sensitivity. The analysis of the transport in the CNT channel using non-equilibrium Green's function (NEGF) formalism confirms single electron sensitivity quantitatively at room temperature. The CNT channel conductance exhibits sensitivity to position of the charge along the channel. The NEGF based analysis is easily extended to the application of CNTFET as a charge sensor. The electrostatics of the CNT-nanocrystal memory was analyzed for transport between nanocrystal and CNT. Despite the nanocrystal being in close proximity of the CNT, it is strongly coupled to the gate electrode electrostatically. This effect is not observed in the planar 2D Si- based nanocrystal memory. It obviates a major trade-off in memory design of scaling the control dielectric to decrease operational voltage, while ensuring low gate leakage and should allow ultra-low voltage operations. Large tunneling current should also enhance write times. Large electric field asymmetry should enable a better write/retention ratio.
In-situ Raman and fluorescence measurements were used to detect optically trapped single-walled carbon nanotubes (SWNTs). The in-situ fluorescence technique provides strong indirect visual evidence of optical trapping of SWNTs by monitoring the fluorescence quenching from a solution containing a mixture of carbon nanotubes and a fluorescent dye. The second monitoring technique uses in-situ Raman spectroscopy to show that in the presence of the optical trap, both the profile and the intensity of the nanotube Raman spectrum changes compared to when the optical trap is off. The Raman monitoring setup consists of two lasers which independently create the optical trapping path and Raman probing path. In this technique the Raman probe is capable of detecting structural information of the carbon nanotubes in the optical trap; therefore providing direct evidence of the local SWNTs concentration variation and chirality distribution. Both methods were used to verify optical trapping of SWNT and to determine the trapping threshold, trapping volume profile, and information on tube concentration change during optical trapping.
Conference Committee Involvement (2)
Nanomaterials Synthesis, Interfacing, and Integrating in Devices, Circuits, and Systems II
9 September 2007 | Boston, MA, United States
Nanomaterial Synthesis and Integration for Sensors, Electronics, Photonics, and Electro-Optics
1 October 2006 | Boston, Massachusetts, United States