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The integration of carbon nanotube (CNT)-based sensor and readout complementary metal–oxide–semiconductor integrated chip (CMOS IC) to detect hydrogen gas in a single chip is presented. First, we have fabricated the CMOS IC using the standard 0.35-\mu \m CMOS process. Then, we have built 8 \times 8 CNT-based sensor cells on it using a proposed tractable postprocessing strategy and judicious electrode scheme. The fabricated sensor IC can operate down to 10-ppm concentration of hydrogen in air as a hydrogen sensor. This paper is expected to have a major impact upon the integration of the CNT technology with CMOS technology and be extended to the development of CMOS IC integrated with various nanomaterials. [ABSTRACT FROM AUTHOR]

A carbon nanotube network device having concentric-shaped electrodes (source and drain) is analyzed to examine the “self-gating” effect of various pH buffer solutions on its electrical properties. Using the 2-D homogeneous percolation theory, current–voltage characteristics of the devices are described as the classical MOSFET formula, in which the device is modeled as the p-type transistor with positive threshold voltage and the gate is tied with the drain (at positive bias) or source (at negative bias). To determine the apparent threshold voltage change due to the corresponding pH value, the \partial VD/\partial ID (VD: drain voltage; ID: drain current) curve is extracted from the measured current–voltage characteristics to find VD\SAT (= - VTH, VGS = \0). A threshold voltage shift according to the pH value is observed without an external gate electrode, showing the possibility of relaxing the requirement of the external gate electrode. By grafting protonation/deprotonation which occurs in the carboxylated single-walled carbon nanotubes, the decaying current as pH increases is explained. Better sensitivity according to the operation regime is examined by the device modeling. [ABSTRACT FROM PUBLISHER]

We presented an approach for the activation of aluminum (Al) alloy using palladium (Pd) and the subsequent gold (Au) electroless plating (ELP) for complementary metal oxide semiconductor (CMOS)-based sensor applications. In this study, CMOS process compatible Al patterned chips were used as substrates for easy incorporation with existing CMOS circuits. To improve the contact resistance that arose from the Schottky barrier between the metal electrodes and the single-walled carbon nanotubes (SWCNTs), electroless deposition of gold that has a higher work function than Al was adopted because the SWCNTs has p-type semiconductor properties. Each step of the Au ELP procedure was studied under various bath temperatures, immersion times, and chemical concentrations. Fine Pd particles were homogeneously distributed on the Al surface by the Pd activation process at room temperature. Au ELP allowed selective deposition of the Au film on the activated Al surface only. The SWCNT networks formed on the Au plated chip by a dip-coating method showed improved contact resistance and resistance variation between the Au electrode and SWCNTs. We also tried SWCNT decoration with the Au particle using the upper Au ELP method, which was expected to be applied in various areas including field-effect transistors and sensor devices. [ABSTRACT FROM AUTHOR]

Abstract: A single-walled carbon nanotube (SWCNT) film was formed on a glass substrate by using the dip-coating method and the resulting material used as a transparent glass heater. The heaters have an optical transparency above 95% in visible light. Their performance was investigated by measuring their heating/cooling characteristics and thermal resistance. They have a heating performance that is ∼70% higher than that of Pt film heaters, which are widely used. The thickness dependence of the thermal resistance is observed, and can be understood in relation to heat-transfer losses that are related to the porous structure of the SWCNT film. The stability and reliability of the heater were also investigated. [ABSTRACT FROM AUTHOR]