Abstract
Highly sensitive and selective gas and volatile organic compound (VOC) sensor platforms with fast response and recovery kinetics are in high demand for environmental health monitoring, industry, and medical diagnostics. Among the various categories of gas sensors studied to date, field effect transistors (FETs) have proved to be an extremely efficient platform due to their miniaturized form factor, high sensitivity, and ultra-low power consumption. Despite the advent of various kinds of new materials, silicon (Si) still enjoys the advantages of excellent and reproducible electronic properties and compatibility with complementary metal–oxide–semiconductor (CMOS) technologies for integrated multiplexing and signal processing. This review gives an overview of the recent developments in Si FETs for gas and VOC sensing. We categorised the Si FETs into Si nanowire (NW) FETs; planar Si FETs, in which the Si channel is either a part of the silicon on insulator (SOI) or the bulk Si, as in conventional FETs; and electrostatically formed nanowire (EFN) FETs. The review begins with a brief introduction, followed by a description of the Si NW FET gas and VOC sensors. A brief description of the various fabrication strategies of Si NWs and the several functionalisation methods to improve the sensing performances of Si NWs are also provided. Although Si NW FETs have excellent sensing properties, they are far from practical realisation due to the extensive fabrication procedures involved, along with other issues that are critically assessed briefly. Then, we describe planar Si FET sensors, which are much closer to real-world implementation. Their simpler device architecture combined with excellent sensing properties enable them as an efficient platform for gas sensing. The third category, the EFN FET sensors, proved to be another potential platform for gas sensing due to their intriguing properties, which are elaborated in detail. Finally, the challenges and future opportunities for gas sensing are addressed.
Highlights
Gas sensors based on field effect transistors (FETs) technology provide a potential platform due to their high sensitivity, possibility of chip-scale miniaturization and ultralow power consumption
The current review presented the recent developments in Si FETs
The current review presented the recent developments in Si FETs for gas and volatile organic compound (VOC) sensing
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. There is always an urgent demand for the development of a chemical/gas sensor with a low detection limit (ideally trace-level molecule detection), high sensitivity, fast response and recovery times, minimum drift, large dynamic range and excellent selectivity to the target analyte under different ambients (dry/humid). Enhanced sensing performances in terms of sensitivity, response and recovery times have been achieved by such sensors due to the large surface-to-volume ratio of these materials, enabled by nanoscale dimensions coupled with the FET architecture. This review article highlights the recent advances in the development of Si FET devices for sensing gas and VOC for various applications. We believe that this article will give a broad outlook to readers on the recent technological advancements in Si FET-based sensors for gas and VOC sensing and pave the way for future developments of gas and VOC sensors
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