Ppb-Level Selective Detection of Aniline and Trimethylamine Using a Ga ₂ O ₃ /GaON Heterojunction with Enhanced Interfacial Charge Modulation

Selective detection of trace volatile organic compounds such as aniline (AN) and trimethylamine (TMA) remains challenging due to their similar chemical properties. Here, we address this discrimination using a Ga 2 O 3 /GaON heterojunction sensor that enables dual-mode detection with switchable selectivity: under 450 nm light at room temperature, it selectively detects AN, while at 160 °C, it exhibits strong specificity toward TMA, achieving 1 ppb detection limits for both. In situ infrared spectroscopy and density functional theory calculations show that distinct Fermi-level hybridization states activate dual N−H···O and N−Ga interfacial pathways. Integrated with an artificial neural network, the system classifies mixtures of AN and TMA with 93.5% accuracy. This work establishes a reconfigurable platform for selective VOC discrimination with potential applications in environmental monitoring and intelligent electronic olfaction.