Deterministic fabrication of carbon nanotube probes using the dielectrophoretic assembly and electrical detection

We report the controlled dielectrophoretic assembly for the deterministic fabrication of carbon nanotube (CNT) probes. Electrical detection was applied to the dielectrophoretic assembly of CNT probes. Dielectrophoretic manipulation with an ac electric field of 5 MHz was used to form the CNT bridge across oppositely aligned tungsten tips (W-tips). A dc electric field was simultaneously applied to monitor the direct current flowing through the gap. The detected nanocurrent reveals that the CNT bridge is formed between W-tips in real time. We compared current data with bundle diameter of CNT probes in field emission scanning electron microscopy (FE-SEM) images. As the number of assembled CNTs increased, current was increased. With the obtained linear relationship, the number of the attached CNTs can be estimated without confirmation of the FE-SEM image. This combined use of the current detection method with dielectrophoretic manipulation will provide a reliable process for the fabrication of CNT probes.