Surface engineered Schottky contact for boosting performance parameters of Al-doped ZnON thin-film transistors

In this study, AlZnON thin-film transistors (TFTs) were fabricated by incorporating aluminum into the ZnON semiconductor and further Schottky contact on the surface of the channel is implemented to enhance the electrical and optical performance of the device. The presence of Al in the thin film improves the reliability of the TFT by stabilizing the nitrogen bond. Further, the optical transmittance improved to 90% from 80% and the bandgap increased to 2.48 eV from 1.89 eV with the doping of Al. The effects of the work function and the widths of the Schottky metal contact on the device characteristics are also investigated. The optimum structure is realized with high work function (5.65 eV) platinum (Pt) metal contact which was positioned at the center of the channel and the width of the Schottky contact was 0.25 times the length of the channel. With the encapsulation of this optimum surface-engineered Schottky contact (SESC) in the device, the field effect mobility increased from 27.3 to 43.9 cm²V^-1·s^-1, the subthreshold swing reduced from 196 to 113 mV dec^-1, threshold voltage changed from -0.13 to 0.12 V and the on-off current ratio improved from 4.13 × 10⁶to 1.03 × 10⁸. The substantial enhancement of transistor performance is achieved through the utilization of a high-work function metal layer, which generates a larger depletion region in the channel, and by precisely controlling the width of the Schottky contact at the channel's center, the depletion region is optimized to suppress off-current while maintaining improved field effect mobility. From the above result, it is evident that the proposed SESC in Al-doped ZnON TFT is a promising candidate for next-generation display application.