Tuning the electrical performance and bias stability of a semiconducting SWCNT thin film transistor with an atomic layer deposited AlZrOx composite

Abstract

Solution-processed semiconducting single-walled carbon nanotube (s-SWCNT) thin film transistors (TFTs) based on different atomic layer deposited AlZrO_x insulators are fabricated and characterized. It is found that increasing the Al concentration in the AlZrO_x insulator can reduce leakage current and decrease the surface roughness of the AlZrO_x insulator. Compared with the device with a ZrO₂ insulator, the electrical performance, including subthreshold swing, I_on/I_off and hysteresis, and negative bias stability of s-SWCNT TFTs with the AlZrO_x insulator has been significantly improved. The s-SWCNT TFT based on AlZrO_x with a ZrO₂/Al₂O₃ cycle ratio of 1/2 reveals a superior electrical performance with an average mobility of 35.2 cm² V⁻¹ s⁻¹, a high on/off ratio of 3.7 × 10⁵, a low subthreshold swing of 0.09, a small hysteresis of 0.1 V, and a small threshold voltage shift of 1.62 V under a negative bias stress of −3 V for 1800 s. The improvement of electrical performance and stability for the s-SWCNT TFT with the AlZrO_x insulator is attributed to the smooth surface and less AlZrO_x/s-SWCNT interface traps. Our results suggest that using a AlZrO_x film as a gate insulator can be a useful technique to achieve high performance and more reliable solution-processed s-SWCNT TFTs.