Breakdown of metallic single-wall carbon nanotube paths by NiO nanoparticle point etching for high performance thin film transistors

A phenomenological model for selective growth of semiconducting single-walled carbon nanotubes based on catalyst deactivation

A method for the selective semiconducting single-walled carbon nanotube (SWCNT) growth over a continuous range from 67% to 98%, within the diameter range of 0.8-1.2 nm, by the use of a "catalyst conditioning process" prior to growth is reported. Continuous control revealed an inverse relationship between the selectivity and the yield as evidenced by a 1000-times difference in yield between the highest selectivity and non-selectivity. Further, these results show that the selectivity is highly sensitive to the presence of a precise concentration of oxidative and reductive gases (i.e. water and hydrogen), and the highest selectivity occurred along the border between the conditions suitable for high yield and no-growth. Through these results, a phenomenological model has been constructed to explain the inverse relationship between yield and selectivity based on catalyst deactivation. We believe our model to be general, as the fundamental mechanisms limiting selective semiconducting SWCNT growth are common to the previous reports of limited yield.

Gate-Free Electrical Breakdown of Metallic Pathways in Single-Walled Carbon Nanotube Crossbar Networks

Aligned single-walled carbon nanotubes (SWNTs) synthesized by the chemical vapor deposition (CVD) method have exceptional potential for next-generation nanoelectronics. However, the coexistence of semiconducting (s-) and metallic (m-) SWNTs remains a considerable challenge since the latter causes significant degradation in device performance. Here we demonstrate a facile and effective approach to selectively break all m-SWNTs by stacking two layers of horizontally aligned SWNTs to form crossbars and applying a voltage to the crossed SWNT arrays. The introduction of SWNT junctions amplifies the disparity in resistance between s- and m-pathways, leading to a complete deactivation of m-SWNTs while minimizing the degradation of the semiconducting counterparts. Unlike previous approaches that required an electrostatic gate to achieve selectivity in electrical breakdown, this junction process is gate-free and opens the way for straightforward integration of thin-film s-SWNT devices. Comparison to electrical breakdown in junction-less SWNT devices without gating shows that this junction-based breakdown method yields more than twice the average on-state current retention in the resultant s-SWNT arrays. Systematic studies show that the on/off ratio can reach as high as 1.4 × 10(6) with a correspondingly high retention of on-state current compared to the initial current value before breakdown. Overall, this method provides important insight into transport at SWNT junctions and a simple route for obtaining pure s-SWNT thin film devices for broad applications.