Spatially Selective Guided Growth of High-Coverage Arrays and Random Networks of Single-Walled Carbon Nanotubes and Their Integration into Electronic Devices

摘要

Thin films of single-walled carbon nanotubes (SWNTs) can provide semiconducting and/or conducting components of passive and active (e.g.,transistors) electronic devices.Potential applications range from large-area,mechanically flexible systems,where semiconducting SWNT films could provide advantages over conventional small-molecule or polymer semiconductors,to high-performance devices,where they could provide alternatives to large-grained polysilicon or even single-crystal silicon.For the former class of application,random networks of SWNT might offer sufficient performance.For the latter,densely packed aligned arrays of SWNT are preferred.Forming such arrays,patterning their coverage,and,possibly,interfacing them with SWNT networks represent significant experimental challenges.Modest degrees of alignment and coverage can be achieved by controlled deposition of SWNTs from solution suspensions or by specialized growth methods.A new technique for generating arrays uses chemical vapor deposition (CVD) of SWNTs on single-crystal substrates of sapphire or quartz.Optimized CVD growth on quartz can yield well-aligned arrays over large areas and with coverages up to 1 SWNT/mum.The coverage can be increased beyond this level,but only at the expense of degraded alignment,due possibly to detrimental effects of interactions between growing SWNTs and unreacted catalyst particles.We report here a method that avoids these problems by spatially patterning the catalyst.The strategy yields perfectly aligned,high-coverage arrays of SWNTs in well-defined geometries;it can also,in the same growth step,produce dense,random networks of SWNTs self-aligned and electrically interfaced to these arrays.The geometries of these SWNT films enable their easy integration into high-performance,planar devices.