All-2D van Der Waals Heterostructure-Based Gate-Sensitive Field-Effect Transistor Platform for Ultrasensitive and Selective Hydrogen Sensing

The rapid development of the Internet of Things (IoT) and smart industrial systems has created an urgent demand for high-performance gas sensors capable of room-temperature operation with low power consumption. To date, while field-effect transistor (FET) architectures have demonstrated remarkable capabilities in addressing key challenges related to miniaturization, power consumption, and sensitivity, the conventional designs' critical dependence on channel materials for selectivity and stability imposes stringent selection criteria, which significantly limits their application scope. Here, we report an atomically thin all-2D gate-sensitive field-effect transistor (GS-FET) based on an h-BN/MoS₂ heterostructure. This design decouples the functions of chemical recognition and charge transport, which not only ensures the stability of the channel material but also allows for flexible tuning of selectivity. Moreover, the atomically thin architecture enables ultrasensitive detection capabilities. Devices with two distinct floating-gate materials (1 nm-thick Ni5Pd95 alloy and Pt) were fabricated, and combined DFT calculations and experimental measurements demonstrate that Ni5Pd95-based and Pt-based devices are optimized for high sensitivity (0.056%/ppm) and fast response/recovery kinetics, respectively. Systematic studies reveal that the thickness-dependent capacitive coupling of the h-BN dielectric provides an additional degree of freedom for sensitivity tuning, while its atomically flat interface minimizes charge scattering and enhances carrier mobility. Furthermore, the h-BN-encapsulated device exhibits superior humidity resistance and long-term stability. This work establishes a universal materials platform for gas sensing that combines the exceptional properties of 2D materials with unique device architecture, opening new possibilities for high-performance environmental monitors, industrial safety systems, and wearable health diagnostics.