Enhanced Operational Stability of Flexible Carbon Nanotube Thin Film Transistors Using Low-Temperature Post-Treatment

Abstract

Carbon nanotubes (CNTs) have been extensively investigated as channel materials for flexible electronics, owing to their inherent flexibility, high carrier mobility, ultrathin body, and solution-based, low-temperature processibility. However, achieving robust operation of CNT thin-film transistors (TFTs) under repeated bias cycling in air, a crucial requirement for complex and large-scale circuits, remains a challenge. In this work, we present a low-temperature hexamethyldisilazane (HMDS) post-treatment (150 °c) to enhance the robustness of flexible, bottom-gated CNT TFTs. This treatment significantly reduces device hysteresis and improves threshold voltage (V_th) stability under repeated bias cycling, decreasing the relative standard deviation (S_r) of V_th from 136% to 34.1% and from 77.3% to 4.23% under different measurement modes. The mechanisms underlying this V_th stability enhancement are primarily attributed to a significant reduction in device surface traps: (1) prolonged 150 °C post-treatment in a vacuum oven promotes the desorption of oxygen and water molecules from the active layer and dielectric surface; (2) HMDS reacts with polar hydroxyl groups on the device surface, generating hydrophobic, non-polar methyl groups, thereby reducing surface charge accumulation; and (3) the hydrophobic nature of the HMDS layer on the device surface contributes to insulating the device from ambient oxygen and water molecules.