Light‐Assisted and Gate‐Tunable Oxygen Gas Sensor Based on Rhenium Disulfide Field‐Effect Transistors

Abstract

Oxygen sensors are essential for a wide range of applications related to, for example, medicine, automobiles, food, and the environment. [1-6] Over the past century, sensors have verified oxygen concentrations using chemical, optical, or electrical approaches. [7,8] Of these approaches, the field-effect transistor (FET) has been widely used in gas sensor applications. [9-11] This is because of its easy incorporation into integrated circuits and well-developed fabrication process. Moreover, current modulation by gate biasing and room-temperature operation provide the advantages of a long device lifetime and low power consumption. [12] Currently, 2D materials are being intensively studied for use in gas sensor devices because of their chemical, physical, optical, and electronic features. [13-16] In other words, 2D materials are promising platforms for gas sensing devices because of their naturally high surface-area-to-volume ratio, which results in high sensitivity. In particular, transition metal dichalcogenides (TMDCs) have a finite bandgap in the 0.2-3.0 eV range depending on the constituent materials and their numbers of layers, [17-19] and they could be used for an FET-based gas sensor. Although the enhancement of the gas sensitivity of TMDC-based FETs by light illumination and gate biasing [20-25] has been reported, the mechanism and roles of their combined effects are not yet understood. In this regard, among the TMDCs, rhenium disulfide (ReS 2) is a promising candidate for a light-assisted and gate-tunable oxygen sensor. This is because ReS 2 offers direct bandgap matching with the visible light range regardless of thickness unlike other TMDCs. [26-28] Therefore, ReS 2 is an ideal material that offers an optimal tradeoff relation between the surface-area-to-volume ratio (thin layer required) and the charge carrier density with the optical absorption (thick layer required) toward realizing a high-performance gas sensor based on a light-assisted and gate-bias operation. In this study, we investigated ReS 2 FET-based oxygen sensor devices. The sensing performance, including response, sensitivity, stability, and durability, was studied in a systematic manner. We focused particularly on the light illumination and gate voltage dependence to clarify their roles in the sensing mechanism. As a result, a practical sensitivity of 0.01% ppm À1 was achieved for oxygen gas by combining light illumination and a positive gate voltage, which outperform over previous reports. [29,30] This research also contributes to an in-depth understanding of the roles of light illumination and gate biasing, leading to the development of a high-performance gas sensor based on TMDC FETs. Figure 1a shows a homemade chamber setup (dimensions: 9.0 Â 6.0 Â 2.5 cm 3) that we used for the ReS 2-FET-based oxygen sensor measurements (see the detailed preparation, fabrication, and sensing measurements of the sensor in the Experimental Section). Figure 1b shows a Raman spectrum of the ReS 2 nanosheet, which displays 18 first-order modes within 100À4...

1D and 2D Field Effect Transistors in Gas Sensing: A Comprehensive Review

“…ReS 2 was recently used as the sensing channel in FETs. [ 341–344 ] Yang et al. reported on the use of a n‐type ReS 2 ‐FET for the sensing of RH level in the range 0 to 100%.…”

“…Improved sensing performance of a ReS 2 ‐FET with gate biasing and light irradiation was also demonstrated for O 2 sensing. [ 342 ]…”

“…More recently, a number of TMDs, e.g., MoS 2 , [ 59,304,309–331 ] MoTe 2 , [ 336–340 ] and ReS 2 , [ 341–344 ] and post TMDs, e.g., SnS 2 , [ 352–354 ] have been also extensively studied for fabrication of 2D FET gas sensors, thanks to their excellent electronic properties allowing to achieve I ON / I OFF >100. Similarly to graphene, TMD‐FET sensors with high sensitivity and selectivity were demonstrated through physical functionalization with metal, [ 59,317 ] semiconductive, [ 318 ] and organic [ 320,324 ] NPs (Figure 34e).…”

Enhanced Selectivity in Volatile Organic Compound Gas Sensors Based on ReS2-FETs under Light-Assisted and Gate-Bias Tunable Operation

“…Meanwhile, the thickness must be monolayer for other conventional TMDCs like MoS 2 or WS 2 to get direct band gaps. − Then, the light absorption becomes less effective. Therefore, ReS 2 is a promising material overcoming the tradeoff relationship between the charge carrier density with the light absorption (thick layer and direct band gap required) and high surface-area-to-volume ratio (thin layer required) for realizing a single-device operation of selective and sensitive VOC sensors based on the effective response of ReS 2 to light illumination. , …”

“…Therefore, ReS 2 is a promising material overcoming the tradeoff relationship between the charge carrier density with the light absorption (thick layer and direct band gap required) and high surface-area-to-volume ratio (thin layer required) for realizing a singledevice operation of selective and sensitive VOC sensors based on the effective response of ReS 2 to light illumination. 36,37 Herein, the advantages of the effective drain current response of ReS 2 to light illumination are highlighted to enhance the gas selectivity performance of a ReS 2 -FET sensor device. The drain current response of the ReS 2 -FET sensor to adsorbed molecules is modulated using light illumination based on different gas species.…”