Study on dielectric properties of PVP and Al2O3 thin films and their implementation in low-temperature solution-processed IGZO-based thin-film transistors

In the present work, we investigated the dielectric properties of solution-processed Poly-(4-vinylphenol) (PVP), and atomic layer deposited (ALD) alumina (Al2O3) thin films. Later, we integrate these dielectric materials into a thin-film transistor (TFT) device fabricated on a glass substrate using solution-processed indium gallium zinc oxide (IGZO) as a semiconductor. Both PVP and Al2O3 films show good dielectric behavior with minimum leakage and capacitance densities of 7.0 nF/cm2 and 1.034×10-7\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$1.034 \times {10}^{-7}$$\end{document} F/cm2, respectively. A bottom source/drain top-gate transistor based on PVP as gate insulator operates in the linear region and demonstrates highly negative threshold voltage values beyond − 40 V. On the other hand, the bottom-gate top source/drain transistor based on Al2O3 gate dielectric demonstrates good saturation behavior with saturation current and saturation mobility of 4.16×10-4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$4.16 \times {10}^{-4}$$\end{document} A and 2.203 cm2/Vs, respectively. Further, using the photochemical activation method, the processing temperature of IGZO thin films is reduced to 325 °C from 400 °C. Low-temperature processed IGZO TFTs also show good saturation behavior with low positive threshold voltage values. However, it is achieved at the expense of saturation mobility which decreases to 0.557 cm2/Vs. Our study presents the possibility of producing organic–inorganic hybrid low-cost, and high-performance devices for upcoming flexible electronics.