Single-ion adsorption and switching in carbon nanotubes

Adam W Bushmaker,Jihan Chen,Stephen B Cronin,Don Walker,Vanessa Oklejas,Alan R Hopkins

doi:10.1038/ncomms10475

Abstract

Single-ion detection has, for many years, been the domain of large devices such as the Geiger counter, and studies on interactions of ionized gasses with materials have been limited to large systems. To date, there have been no reports on single gaseous ion interaction with microelectronic devices, and single neutral atom detection techniques have shown only small, barely detectable responses. Here we report the observation of single gaseous ion adsorption on individual carbon nanotubes (CNTs), which, because of the severely restricted one-dimensional current path, experience discrete, quantized resistance increases of over two orders of magnitude. Only positive ions cause changes, by the mechanism of ion potential-induced carrier depletion, which is supported by density functional and Landauer transport theory. Our observations reveal a new single-ion/CNT heterostructure with novel electronic properties, and demonstrate that as electronics are ultimately scaled towards the one-dimensional limit, atomic-scale effects become increasingly important.

Highlights

Single-ion detection has, for many years, been the domain of large devices such as the Geiger counter, and studies on interactions of ionized gasses with materials have been limited to large systems
Electronic conduction in one-dimensional (1D) channels has been the focus of many research efforts over the past 15 years, and during that time carbon nanotubes (CNTs) have often served as the prototypical system for studying 1D conduction
The reason for the strong interest is both because of the interesting fundamental physics that occur in such systems[1,2,3] and because of the enhanced functional performance that has been predicted to occur in CNT-based field effect transistors (FETs) such as high linearity and high operation frequency[4,5]

Summary

Introduction

Single-ion detection has, for many years, been the domain of large devices such as the Geiger counter, and studies on interactions of ionized gasses with materials have been limited to large systems. CNT FETs are being considered as a promising new technology for next-generation micro- and nano-electronic devices and circuitry Owing to their small physical size, the conductivity of CNTs and other molecular systems is highly susceptible to changes in charge states of defects nearby or in contact with the material[9], or even by direct chemical activity on the surface of the CNT10,11. Single neutral atom detection techniques have shown only small, barely detectable responses[14,15,16,17], and there is relatively little information in the literature on ion adsorption on the surfaces of solids from gas This is despite the various industrial techniques that make use of ions from corona discharge for surface treatment, such as a surface treatment of polymers to improve adhesion and other surface properties[18], and surface charging of insulators as a contactless electrode for both processing and characterization in the semiconductor microelectronics industry[19,20]. These experimental results are modelled computationally using density functional theory (DFT) and Landauer electrical transport theory

Methods

Results

Conclusion