Ongi Englander

Local synthesis of silicon nanowires and carbon nanotubes on microbridges

them with microelectronics to form a complete system. 2,5‐9 Current synthesis processes for silicon nanowires and carbon nanotubes require high temperature furnaces that could damage pre-existing microelectronics. We present an approach that allows the synthesis, in a room temperature chamber, of a desired nanostructure at a prespecified location while eliminating the requirement of later assembly processes. This localized selective synthesis process is capable of direct integration of either silicon nanowires or carbon nanotubes with larger-scale systems, such as foundry-based microelectronics processes. The approach is based on localized resistive heating of suspended microstructures in a roomtemperature chamber @Fig. 1~g!# to activate vapor-deposition synthesis and yield either silicon nanowires or carbon nano

Room temperature local synthesis of carbon nanotubes

We report the synthesis of carbon nanotubes (CNT) by localized resistive heating of a MEMS structure in a room temperature chamber. This is the first known vapor-deposition CNT growth method that does not require globally elevated temperatures. The localized, selective, and scalable process is compatible with on-chip microelectronics and removes necessity of post-synthesis assembly of nanostructures to form integrated devices. Synthesized nanotube dimensions are 5-50 nm in diameter and up to 7 /spl mu/m in length. Growth rates of up to 0.25 /spl mu/m/min were observed. This accomplishment makes possible the direct integration of CNT devices with on-chip transduction, readout, processing, and communications circuitry, facilitating integration of nanotechnology with larger-scale systems.

The integration of nanowires and nanotubes with microstructures

A technique for the localised synthesis, self-assembly and direct integration of nanostructures with microstructures employing the localised synthesis of nanostructures onto Microelectromechanical Systems (MEMS) structures is demonstrated. The in-situ guided growth process of the nanostructures is accomplished using a locally applied electric-field realised by using the MEMS structures as electrodes. The self-assembly and self-terminated contact process of nanostructures is achieved when the hot nanostructure makes contact with the cold MEMS structure. This approach is flexible and both Silicon Nanowires (SiNWs) and Carbon Nanotubes (CNTs) have been successfully integrated to form Nanoelectromechanical Systems (NEMS) devices. These systems are potentially available for sensing applications with or without further functionalisation. As such, this approach mitigates integration and manufacturing difficulties which currently plague the fabrication of nanoscale devices.

Silicon nanowire-based nanoactuator

A new class of nanoactuator based on the bimetal thermal effect of chromium-coated silicon nanowire has been demonstrated. The nanoactuator is fabricated by the localized synthesis process of silicon nanowires and coating them with a 5 nm-thick layer of chromium. Actuation occurs when the supporting microheater is heated locally by resistive joule heating which causes the nanowires to deflect due to the difference in the coefficient of thermal expansion (CTE) between chromium and silicon. Experimentally, the maximum measured deflection of a 3.66 /spl mu/m-long silicon nanowire is 1.52 /spl mu/m under a power input of 31.4 mW to the microheater.

Post-Processing Techniques for the Integration of Silicon Nanowires and MEMS

Three post-processing techniques key for the integration of nanostructures and MEMS (Microelectromechanical Systems) are presented. The objective is to develop a toolset for integrated NEMS (Nanoelectromechanical Systems) design and processing. More specifically, experimentation is focused on (1) local contact metallization, (2) global metallization for rapid system functionalization and (3) aqueous treatment of self-assembled and suspended silicon nanowires between two MEMS bridges. These techniques are evaluated for their effectiveness and compatibility with integrated NEMS. It is found that local contact metallization effectively alleviates inherent problems at the nano-to-micro contact, while the aqueous treatment confirms that nanoscale components of the system exhibit similar response as their microscale counterparts. Further, the global metallization process enables rapid functionalization as demonstrated in a hydrogen sensing experiment.

Localized synthesis of silicon nanowires

Localized resistive heating of microstructures has been used to activate vapor-deposition synthesis of silicon nanowires in a room-temperature chamber. The process is localized, selective, scalable and compatible with on-chip microelectronics and, in addition, removes necessity of post-synthesis assembly of nanowires to accomplish integrated nano-electromechanical systems. Synthesized nanowires with dimensions of 30-80 nm in diameter and up to 10 /spl mu/m in length have been successfully demonstrated and growth rates of up to 1/spl mu/m/min have been observed. This new class of manufacturing method enables direct integration of nanotechnology with larger-scale systems for potential sensing and actuation applications.

Direct Synthesis and Self-Assembly of Silicon Nanowires

The direct synthesis and self-assembly of silicon nanowires to yield a two-terminal, nano-to-micro integrated system has been demonstrated. The process takes advantage of localized heating to initiate and sustain a bottom up nanowire synthesis mechanism. As soon as the nanowire synthesis process is complete, the integrated system is ready for characterization of mechanical and electrical properties as well as functionalization for sensing applications. The process is CMOS compatible and eliminates the nano-to-micro contact formation process that is currently required of traditional processes.Copyright