In-situ Opening Aligned Carbon Nanotubes and Applications for Device Assembly and Field Emission

Abstract

Carbon nanotubes (CNTs) have been proposed for applications in microelectronic applications, especially for electrical interconnects and nanodevices, due to their excellent electrical, thermal and mechanical properties. Usually, the CNTs produced by arcing, laser ablation or chemical vapor deposition (CVD) are inevitably close-ended. Due to the weak coupling of the individual walls and close ends, it leads to conclusions that only the outer wall of multi-walled CNT is contributed to the current-carrying capacity. However, recent research shows that each wall of the multi-walled CNTs contributes to the saturation current to obtain a very high current-carrying capacity, i.e., the multichannel electron transport could be achieved by opening multi-walled CNTs. The previous process to open the CNTs can't be applied to the aligned CNTs, since they will damage the original alignment of CNTs. In this paper, we for the first time report a simple process to achieve simultaneous CNT growth and opening of the CNT ends, while keeping alignment of the original CNT films/arrays. The addition of relatively low reactivity oxidizing agents (water) into the reaction furnace has been demonstrated the feasibility. The as-grown CNTs were characterized by high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM). Also, we proposed using novel CNT transfer technology, enabled by open-ended CNTs, to circumvent the high carbon nanotube (CNT) growth temperature and poor adhesion with the substrates that currently plague CNT implementation. The process is featured with separation of high-temperature CNT growth and low-temperature CNT device assembly. Field emission testing of the as-assembled CNT devices is in a good agreement with the Fowler-Nordheim (FN) equation, with a field enhancement factor of 4540. This novel technique shows promising applications for positioning CNTs on temperature-sensitive substrates, and for the fabrication of field emitters, electrical interconnects, thermal management structures in microelectronics packaging