The Role of Oxygen at the Interface between Titanium and Carbon Nanotubes

TL;DR

This study investigates how oxygen affects the interface between titanium and carbon nanotubes, revealing that oxygen weakens their interaction and influences contact quality, with implications for device fabrication.

Contribution

It provides new insights into the role of oxygen at Ti-CNT interfaces and suggests improved surface treatment methods for better electrical contacts.

Findings

Oxygen weakens Ti-CNT interactions at the interface.

Charge transfer and carbide formation occur at the interface.

Pre-treatment and vacuum conditions influence contact quality.

Abstract

We study the interface between carbon nanotubes (CNTs) and surface-deposited titanium using electron microscopy and photoemission spectroscopy, supported by density functional calculations. Charge transfer from the Ti atoms to the nanotube and carbide formation is observed at the interface which indicates strong interaction. Nevertheless, the presence of oxygen between the Ti and the CNTs significantly weakens the Ti?CNT interaction. Ti atoms at the surface will preferentially bond to oxygenated sites. Potential sources of oxygen impurities are examined, namely oxygen from any residual atmosphere and pre-existing oxygen impurities on the nanotube surface, which we enhance through oxygen plasma surface pretreatment. Variation in literature data concerning Ohmic contacts between Ti and carbon nanotubes is explained via sample pre-treatment and differing vacuum levels, and we suggest improved treatment routes for reliable Schottky barrier-free Ti?nanotube contact formation.