Solution-processed high stability top-gate W and F co-doped ZnSnO thin film transistors

In this work, top-gate structured W: F co-doped Zn–Sn–O (ZTO) thin-film transistors (TFTs) with excellent stability are prepared by the solution process. Comparing with the undoped ZTO TFT, the mobility of W: F co-doped ZTO TFTs was up from 1.87 to 3.14 cm² V⁻¹ s⁻¹, and the subthreshold swing decreases from 0.192 to 0.157 V/dec. Moreover, the W: F co-doped ZTO TFTs exhibit a small V_th shift of −0.09 V under negative bias illumination stress, which is close to one of the TFTs prepared by the traditional vacuum process. X-ray photoelectron spectroscopy and capacitance–voltage examination revealed that the enhanced stability is due to the fact that W: F co-doping can effectively suppress defect states in ZTO films. The results manifest that W: F co-doping may be a promising method for enhancing the stability of TFTs with the top-gate structure.