Carbon nanotube engineering via template CVD.

摘要

The development of rational carbon nanotube (CNT) synthesis---the controllable growth of nanotubes and their multiply branched interconnections---would be a revolutionary advance for nanotechnology. In this work a route to rational synthesis of CNTs is presented which is based on nanoscale chemical vapor deposition (CVD) templating. The nanotemplating technique produces precisely positioned and aligned CNTs with tightly controlled diameters and lengths, which are integrated onto a substrate as ultra-dense arrays. By controlling the shape of the nanotemplate it is also possible, for the first time, to directly grow branched CNTs with one or multiple branching points that can be accurately defined. Thus, nanoscale CVD templating is shown as providing a high-efficiency, parallel process for controlled CNT synthesis that requires minimal post-growth purification.; The processing steps required to fabricate CNTs via nanoscale CVD templating by using anodic aluminum oxide nanopore templates (AAO) as molds for CVD are described. The two main structures enabled by this approach, highly-ordered CNT arrays and Y-junction CNTs, are then characterized structurally via various techniques. Experimental efforts to measure electronic transport in CVD-template grown CNTs are presented with particular emphasis on multi-terminal CNT junctions displaying a unique type of mesoscopic rectification at room temperature that could form the basic elements of future nanoelectronic networks. Theoretical modeling of an important issue for the practical implementation of CNT devices, i.e. doping levels, is presented in the form of a novel self-doping mechanism.