Selective Chemical Vapor Sensing with Few-Layer MoS2 Thin-Film Transistors

TL;DR

This study demonstrates that few-layer MoS2 thin-film transistors can selectively detect various chemical vapors by monitoring conductance, transient response, and current fluctuations, with enhanced stability after aging and surface modification.

Contribution

It introduces a novel multi-parameter sensing approach using MoS2 transistors, including transient and fluctuation analysis, for improved selectivity in chemical vapor detection.

Findings

MoS2 transistors show over two orders of magnitude current change upon vapor exposure.

Surface coating with Al2O3 prevents response, confirming surface interaction importance.

Transient time and current fluctuation spectral density are effective for selectivity.

Abstract

We demonstrated selective gas sensing with MoS2 thin-film transistors using the change in the channel conductance, characteristic transient time and low-frequency current fluctuations as the sensing parameters. The back-gated MoS2 thin-film field-effect transistors were fabricated on Si/SiO2 substrates and intentionally aged for a month to verify reliability and achieve better current stability. The same devices with the channel covered by 10 nm of Al2O3 were used as reference samples. The exposure to ethanol, acetonitrile, toluene, chloroform, and methanol vapors results in drastic changes in the source-drain current. The current can increase or decrease by more than two-orders of magnitude depending on the analyte. The reference devices with coated channel did not show any response. It was established that transient time of the current change and the normalized spectral density of the low-frequency current fluctuations can be used as additional sensing parameters for selective gas detection with thin-film MoS2 transistors.