Abstract
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 AlOx, HfOx, and ZrOx, on the operating characteristics of In2O3 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(2), hence proving suitable, for application in low-voltage n-channel In2O3 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 (mu). To this end mu is found to increase from 1 to 2 cm(2)/Vs for AlOx, 1.8 to 6.4 cm(2)/Vs for HfOx, and 2.8 to 18.7 cm(2)/Vs for ZrOx-based In2O3 TFTs utilizing single and double-layer dielectric, respectively. The proposed method is simple and potentially applicable to other metal oxide dielectrics and semiconductors. (C) 2018 Author(s).