Single-Walled Carbon Nanotube Network Field Effect Transistor as a Humidity Sensor

Prasantha R. Mudimela,Albert G. Nasibulin,Kestutis Grigoras,Vladimir Ermolov,Esko I. Kauppinen,Ilya V. Anoshkin,Aapo Varpula,Anton S. Anisimov,Sergey Novikov

doi:10.1155/2012/496546

Abstract

Single-walled carbon nanotube network field effect transistors were fabricated and studied as humidity sensors. Sensing responses were altered by changing the gate voltage. At the open channel state (negative gate voltage), humidity pulse resulted in the decrease of the source-drain current, and,vice versa, the increase in the source-drain current was observed at the positive gate voltage. This effect was explained by the electron-donating nature of water molecules. The operation speed and signal intensity was found to be dependent on the gate voltage polarity. The positive or negative change in current with humidity pulse at zero-gate voltage was found to depend on the previous state of the gate electrode (positive or negative voltage, respectively). Those characteristics were explained by the charge traps in the gate dielectric altering the effective gate voltage, which influenced the operation of field effect transistor.

Highlights

Single-walled carbon nanotubes (SWCNTs) have a great promise for many applications due to their unique electronic and optical properties [1]
The positive or negative change in current with humidity pulse at zero-gate voltage was found to depend on the previous state of the gate electrode. Those characteristics were explained by the charge traps in the gate dielectric altering the effective gate voltage, which influenced the operation of field effect transistor
The metallic SWCNT conductivity is almost independent of the gate voltage, while that of the semiconducting SWCNTs strongly depends on the gate voltage and usually exhibits a p-type channel behaviour of the transistor (Figure 3) [26]

Summary

Introduction

Single-walled carbon nanotubes (SWCNTs) have a great promise for many applications due to their unique electronic and optical properties [1]. In random SWCNT networks, the properties averaged over a large number of tubes suppress the effects of the SWCNT chirality variation and allows reaching reproducible results [3]. The SWCNT networks are of low cost and exhibit good transparency and high conductivity, making them ideal candidates for various potential applications such as thin film transistors [8, 9], solar cells [10], displays [11], transparent conducting coatings [12, 13], and sensors [4] The latter is very promising, little explored application of the SWCNT films, especially for humidity sensing

Methods

Results

Conclusion