Simulation of environmental impacts on the synthesis of carbyne with more than 6000 atoms for emerging continuously tunable energy barriers in CNT-based transistors

TL;DR

This paper uses Monte Carlo simulations to predict optimal lengths and conditions for synthesizing long carbyne chains within carbon nanotubes, aiming to enable tunable energy barriers in CNT-based transistors.

Contribution

Developed a Monte Carlo model to predict stability and optimal length of long carbynes inside CNTs, facilitating the design of tunable energy barriers in transistors.

Findings

Carbyne stability is affected by CNT porosity, pressure, temperature, and chain length.

Chain-breaking initiates under compression conditions.

Proposed design rules for synthesizing strained carbynes in CNTs.

Abstract

Transistors made up of carbon nanotubes CNT have demonstrated excellent current-voltage characteristics which outperform some high-grade silicon-based transistors. A continuously tunable energy barrier across semiconductor interfaces is desired to make the CNT-based transistors more robust. Despite the direct band gap of carbyne inside a CNT can be widely tuned by strain, the size of carbyne cannot be controlled easily. The production of a monoatomic chain with more than 6000 carbon atoms is an enormous technological challenge. To predict the optimal chain length of a carbyne in different molecular environments, we have developed a Monte Carlo model in which a finite-length carbyne with a size of 4000-15000 atoms is encapsulated by a CNT at finite temperatures. Our simulation shows that the stability of the carbyne@nanotube is strongly influenced by the nature and porosity of the CNT, the external pressure, the temperature and the chain length. We have observed an initiation of chain-breaking process in a compressed carbyne@nanotube. Our work provides much needed input for optimising the carbyne length to produce carbon chains much longer than 6000 atoms at ~300K. Design rules are proposed for synthesizing ~1% strained carbyne@(6,5)CNT as a component in CNT-based transistors to tune the energy barriers continuously.