High-performance IGZO/Ga₂O₃ dual-active-layer thin film transistor for deep UV detection

Owing to the intrinsically wide bandgap and high uniformity, amorphous Ga₂O₃ (a-Ga₂O₃) has been illustrating a great industrial potential for large-area deep ultraviolet (UV) photosensor arrays. However, a seemingly irreconcilable contradiction between high responsivity and long persistent photoconductivity has hampered the growing pace of such devices. In this work, three-terminal InGaZnO (IGZO)/a-Ga₂O₃ dual-active-layer (DAL) transistors were developed to realize the ability of a-Ga₂O₃ as the active layer both in switching and sensing. Benefitting from the introduction of ultrathin IGZO electron reservoir and defect control of a-Ga₂O₃, the DAL device demonstrates more stable and superior gate-control capability with promising performance including high on/off ratio and field-effect mobility of ∼10⁸ and 8.3 cm²/V⋅s, respectively, as well as a small sub-threshold swing (SS) of 0.36 V/dec. Under 254 nm UV illumination, the DAL device manifests a light-to-dark ratio of ∼10⁸, a responsivity of 4.8 × 10³ A W⁻¹, a detectivity of 8 × 10¹⁵ Jones, and a UV/visible rejection ratio (R₂₅₄/R₄₀₀) of 64. The simultaneous achievement of deep UV photo-detection and transistor's switching performance in a-Ga₂O₃ material offers excellent potential for the construction of large-area active-matrix UV photosensor arrays with the simple and low-cost fabrication process.