Au-Nanostructure Decorated MoS2 Field-Effect Transistors for Enhanced Sensing and Discrimination of Volatile Organic Compounds

Abstract

The development of portable, low-power electronic noses for volatile organic compound (VOC) identification is crucial for applications ranging from environmental monitoring to medical diagnostics. Although two-dimensional materials such as molybdenum disulfide (MoS2) are attractive sensing platforms due to their high surface-to-volume ratio and room-temperature operation, pristine devices often exhibit limited sensitivity and poor selectivity. Here, we present a CMOS-compatible, post-fabrication functionalization approach that enhances VOC sensing in MoS2 field-effect transistors (FETs) and introduces Au decoration thickness as an additional tuning parameter for array construction. Specifically, ultrathin gold (Au) layers with precisely controlled nominal thicknesses (1−3 nm) are deposited onto the transistor channel by standard electron beam evaporation. By tuning the nominal Au thickness from 1 to 3 nm, distinct surface morphologies, including nanoparticles, nanoclusters, and interconnected nanoscale networks, are formed on the MoS2 channel. By leveraging thickness-programmed Au functionalization, we build a multi-element sensor array from a single material platform, in which each element shows a distinct electrical response to different VOCs, producing analyte-specific response patterns. The array outputs are further analyzed using machine-learning algorithms, achieving a classification accuracy of 93.75% across six VOCs. This work provides a scalable, fabrication-friendly route to high-performance and discriminative sensor arrays, bridging the gap between emerging 2D materials and practical electronic-nose systems.