High-Performance Top-Gate and Dual-Gate p-Type SnO Thin-Film Transistors Compatible with 350 °C Back-End-of-Line Processes

Integrating high-performance p-type oxide semiconductors into monolithic three-dimensional (3D) architectures remains challenging due to the scarcity of thermally robust p-type materials compatible with back-end-of-line (BEOL) processing. SnO is a promising p-type oxide for thin-film transistors (TFTs); however, its implementation in top-gate and dual-gate architectures remains limited, and high-temperature processing often induces ambipolar conduction that degrades device operation within practical BEOL thermal budgets (∼350 °C). Here, we demonstrate high-performance top-gate and vertically symmetric dual-gate SnO TFTs based on polycrystalline SnO films grown by atomic layer deposition (ALD). The ALD-grown SnO exhibits intrinsic p-type conductivity without postdeposition annealing, enabling top-gate TFTs with on/off ratios up to 105. Vertically symmetric dual-gate TFTs further achieve on/off ratios above 106 and a peak field-effect mobility exceeding 4 cm2/V·s. By replacing Pt with W as the source/drain electrodes, robust p-type conduction is preserved after 350 °C annealing, satisfying BEOL thermal constraints. In addition, the top-gate operation mode suppresses thermally activated electron current by over 3 orders of magnitude. The devices exhibit stable operation under bias stress and long-term storage with good device-to-device reproducibility. These results establish a thermally robust p-type SnO TFT platform for BEOL-compatible monolithic 3D oxide electronics.