The quality of the gate dielectric/semiconductor interface in thin-film transistors (TFTs) is known to determine the optimum operating characteristics attainable. As a result in recent years the development of methodologies that aim to improve the channel interface quality has become a priority. Herein, we study the impact of the surface morphology of three solution-processed high-k metal oxide dielectrics, namely AlO, HfO, and ZrO, on the operating characteristics of InO TFTs. Six different dielectric configurations were produced via single or double-step spin-casting of the various precursor formulations. All layers exhibited high areal capacitance in the range of 200 to 575 nF/cm, hence proving suitable, for application in low-voltage n-channel InO TFTs. Study of the surface topography of the various layers indicates that double spin-cast dielectrics exhibit consistently smoother layer surfaces and yield TFTs with improved operating characteristics manifested, primarily, as an increase in the electron mobility (μ). To this end, μ is found to increase from 1 to 2 cm/Vs for AlO, 1.8 to 6.4 cm/Vs for HfO, and 2.8 to 18.7 cm/Vs for ZrO-based InO TFTs utilizing single and double-layer dielectric, respectively. The proposed method is simple and potentially applicable to other metal oxide dielectrics and semiconductors.
Bibliographical noteKAUST Repository Item: Exported on 2021-02-19
Acknowledgements: A.D.M. and T.D.A. acknowledge the Engineering and Physical Sciences Research Council (EPSRC) grant no. EP/G037515/1. A.D.M. and P.P. acknowledge Vidyasirimedhi Institute of Science and Technology (VISTEC) for funding and the Frontier Research Center (FRC) of VISTEC for instrumentation support. T.D.A. acknowledges the King Abdullah University of Science and Technology (KAUST) for the financial support.