Low temperature and high-performance ZnSnO thin-film transistors engineered by in situ thermal manipulation

Abstract

Thin film transistors (TFTs) with low cost, high mobility and low processing temperature are key enablers for practical application, which are always contradictory. In this work, we achieved high performance of ZnSnO (ZTO) TFT at low processing temperature via an in situ thermal manipulation strategy. The performances of ZTO TFT, the structures and properties of ZTO thin film, and the intrinsic correlations among them are systematically investigated by experimental and theoretical calculation methods. With the elevation of in situ temperature from 25 °C to 250 °C, the field-effect mobility increases first and then declines. As a result, high performance of ZTO TFT with μ_lin of 9.60 cm² V⁻¹ s⁻¹, V_th of −0.29 V, SS of 0.36 V dec⁻¹ and I_on/I_off of 10⁸ are achieved at 150 °C, which also exhibits excellent stability under PBS, NBS and NBIS conditions. The optimal ZTO TFT operates in depletion mode due to the higher number of background carriers. Further investigation indicates that a moderate in situ temperature not only benefits the densification and the local-lattice order of ZTO thin film, but also facilitates the formation and ionization of oxygen vacancy, therefore, resulting in the significant enhancement of electrical performance of ZTO TFT devices. This strategy is generalizable for designing other high-performance amorphous oxide semiconductor (AOS) materials and devices.