Rate-selected growth of ultrapure semiconducting carbon nanotube arrays

Zhenxing Zhu,Nan Wei,Jun Gao,Boyuan Shen,Fei Wei,Rufan Zhang,Yao Wang,Jun Xu,Qian Wen,Silei Sun,Weijun Cheng

doi:10.1038/s41467-019-12519-5

Zhenxing Zhu, Nan Wei + Show 9 more

Open Access

https://doi.org/10.1038/s41467-019-12519-5

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Abstract

Carbon nanotubes (CNTs) are promising candidates for smart electronic devices. However, it is challenging to mediate their bandgap or chirality from a vapor-liquid-solid growth process. Here, we demonstrate rate-selected semiconducting CNT arrays based on interlocking between the atomic assembly rate and bandgap of CNTs. Rate analysis confirms the Schulz-Flory distribution which leads to various decay rates as length increases in metallic and semiconducting CNTs. Quantitatively, a nearly ten-fold faster decay rate of metallic CNTs leads to a spontaneous purification of the predicted 99.9999% semiconducting CNTs at a length of 154 mm, and the longest CNT can be 650 mm through an optimized reactor. Transistors fabricated on them deliver a high current of 14 μA μm−1 with on/off ratio around 108 and mobility over 4000 cm2 V−1 s−1. Our rate-selected strategy offers more freedom to control the CNT purity in-situ and offers a robust methodology to synthesize perfectly assembled nanotubes over a long scale.

Highlights

Carbon nanotubes (CNTs) are promising candidates for smart electronic devices
We describe the decay rate with half-length L0.5, which denotes the length where the CNT quantity (NL) decreases by half compared to that (N0) near the catalyst
Apart from the catalytic effect, the new template plays the ‘affinity’ role to confine the orientation of subsequent C2 addition

Summary

Introduction

Carbon nanotubes (CNTs) are promising candidates for smart electronic devices. it is challenging to mediate their bandgap or chirality from a vapor-liquid-solid growth process. U.S military’s Defense Advanced Research Projects Agency (DARPA) has recently predicted the forthcoming electronics resurgence and sponsored to fabricate faster and smaller CNT chips[6] Such applications may not be accomplished until crucial issues such as precise atom alignment and controlled synthesis based on bandgap and diameter would be resolved. The reported longest length extended to 550 mm with more than ten billion carbon dimers C2 being precisely assembled along one chiral direction[10] On these perfect tubes will ballistic transport be easier to achieve due to a lack of defect-site-induced carrier scattering, and devices integrated on these individual long tubes can possess the best uniformity of performances[11]. Our method provides a strategy to in situ control the s-CNT purity, and reveals a template mechanism to achieve structural control for CNTs of the vapor-liquid-solid growth mode

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Results

Conclusion