Nanosoldering carbon nanotube junctions with metal via local chemical vapor deposition for improved device performance

Carbon nanotube (CNT) network devices are useful in integrated circuits and display drivers, particularly in applications that make use of thin film transistors. However, in such devices, the performance is usually limited by high electrical and thermal resistances at the inter-tube junctions. The current research presents a novel method to improve such resistances using a localized chemical vapor deposition (CVD) process. As these junctions are the most-resistive regions, we are able to locally heat and selectively deposit metals at the junctions by passing currents through the CNT network in the presence of metal CVD precursors in a vacuum environment, thereby nanosoldering the inter-tube junctions. We show that the metals indeed start to form at the junctions, which directly indicates that the inter-tube junctions are indeed the spots of high thermal resistance. We also show that the effects of nanosoldering are dependent on the types of metals deposited, and furthermore, our nanosoldering technique can effectively improve the overall device performance by more than an order of magnitude.