LASER-INDUCED GROWTH OF DIAMETER-MODULATED SINGLE-WALLED CARBON NANOTUBES

摘要

Periodic diameter modulation of individual carbonrnnanotubes (CNTs) by rapid temperature variation inrnlaser-assisted chemical vapor deposition (LCVD)rnprocess was successfully achieved. A CO_2 laser wasrnused to quickly and precisely modulate the growthrntemperature. Due to inverse relationship between therndiameter of SWNTs and the growth temperature,rntapered and diameter-alternating tubes were grown byrnmodulating the CO_2 laser power during the growth.rnThe diameter-modulated SWNTs were grown across arnpair of Mo electrodes to form field-effect transistorsrn(FETs) for investigation of their electrical and opticalrnproperties. Variations in the bandgap of the individualrnsemiconducting SWNTs were detected meaning thernformation of multi bandgaps within a single tube.rnTransmission electron microscopy and Ramanrnspectroscopy were also studied to investigate thernstructural and electronic properties of the structures.