Growth of Close-Packed Semiconducting Single-WalledCarbon Nanotube Arrays Using Oxygen-Deficient TiO2Nanoparticlesas Catalysts.

For the application of single-walledcarbon nanotubes (SWNTs) in nanoelectronic devices, techniques toobtain horizontally aligned semiconducting SWNTs (s-SWNTs) with higherdensities are still in their infancy. We reported herein a rationalapproach for the preferential growth of densely packed and well-aligneds-SWNTs arrays using oxygen-deficient TiO2nanoparticlesas catalysts. Using this approach, a suitable concentration of oxygenvacancies in TiO2nanoparticles could form by optimizingthe flow rate of hydrogen and carbon sources during the process ofSWNT growth, and then horizontally aligned SWNTs with the densityof ∼10 tubes/μm and the s-SWNT percentage above 95% weresuccessfully obtained on ST-cut quartz substrates. Theoretical calculationsindicated that TiO2nanoparticles with a certain concentrationof oxygen vacancies have a lower formation energy between s-SWNT thanmetallic SWNT (m-SWNT), thus realizing the preferential growth ofs-SWNT arrays. Furthermore, this method can also be extended to othersemiconductor oxide nanoparticles (i.e., ZnO, ZrO2andCr2O3) for the selective growth of s-SWNTs,showing clear potential to the future applications in nanoelectronics. [ABSTRACT FROM AUTHOR]