Nanorobotic Manipulator Controlled Nanowire Growth

We report a single tungsten nanowire successfully grown by controlling the distance between the emitter and substrates with a robotic nanomanipulator moved at a speed of 15 nm/s. When we draw the emitter far from the substrates during electron emission, the longest nanowire at the tip can grow continually, because the electron field at the tip is stronger than the other parts of nanowires. Although multiple nanowires grow at the beginning, the result is that only one nanowire can grow continually at the tip of carbon nanotubes (CNTs). We also show tree-like nanowires on the tip of a CNT without inter-electrode control. These nanowires were induced by field emission, with tungsten hexacarbonyl as precursors. The nanowire´s geometric properties were characterized with transmission electron microscopy (TEM) and its composition was detected with TEM energy dispersive X-ray spectrometry (EDS). The EDS spectrum showed that the nanowires are mainly made of tungsten and carbon. The degradation of CNT emitter is an important problem and influences the device´s stability and lifetime. We propose that the growth of nanowires can be used for modifying degraded emitters