Integration of High-Performance FETs and Sensitive Gas Sensors Using Janus WSiGeP₄ for Trace Toxic Gas Detection

Integrating a field-effect transistor (FET) and FET-type gas sensor within a single two-dimensional (2D) semiconducting material is essential for achieving on-chip detection of trace concentrations of toxic gas. This technology allows the output signal of the gas sensor to be amplified directly by the FET on an integrated circuit, enabling complex analyses to be performed in a compact and efficient manner. However, achieving this integration is currently challenging. In this study, using first-principles calculations, we demonstrate that a Janus WSiGeP₄ monolayer with out-of-plane polarization can be utilized to create both a high-performance top-gate FET and an ultrasensitive bottom-gate FET-type gas sensor, thereby facilitating the integration of these two devices. The key performance metrics of the designed FET align with the standards set by the International Technology Roadmap for Semiconductors (ITRS) for high-performance applications, while the gas sensor exhibits high response to both NO and NH₃ gases in the low oxygen air and humid environment with ultrahigh responses of 301.2 and 99.4 toward NO and NH₃ gas, respectively. Our work provides a promising strategy for integrating these two devices within a single 2D material.