Molecularly-thin anatase field-effect transistors fabricated through the solid state transformation of titania nanosheets

TL;DR

This paper reports the fabrication of molecularly-thin anatase phase FETs from Ti0.87O2 nanosheets, demonstrating high mobility and potential for catalytic control, advancing 2D oxide electronics.

Contribution

It introduces a novel solid state transformation method to produce high-quality, monolayer anatase FETs from Ti0.87O2 nanosheets, with improved electronic properties.

Findings

Maximum mobility of ~1.3 cm2V-1s-1

Current on/off ratio of ~10^5

No photocurrent peak at ~2 eV indicating fewer oxygen vacancies

Abstract

We demonstrate the field-effect transistor (FET) operation of molecularly-thin anatase phase produced through solid state transformation from Ti0.87O2 nanosheets. Monolayer Ti0.87O2 nanosheet with a thickness of 0.7 nm is two-dimensional oxide insulators in which Ti vacancies are incorporated, rather than oxygen vacancies. Since the fabrication method, in general, largely affects the film quality, the anatase films derived from Ti0.87O2 nanosheet show interesting characteristics, such as no photocurrent peak at ~2 eV, which is related to oxygen vacancies, and a larger band gap of 3.8 eV. The 10-nm thick anatase FETs exhibit superior transport characteristics with a maximum mobility of ~1.3 cm2V-1s-1 and current on/off ratio of ~105 at room temperature. The molecularly-thin anatase FET may provide new functionalities, such as field-effect control of catalytic properties.