Study on dielectric properties of PVP and Al_2O_3 thin films and their implementation in low-temperature solution-processed IGZO-based thin-film transistors

摘要

In the present work, we investigated the dielectric properties of solution-processed Poly-(4-vinylphenol) (PVP), and atomic layer deposited (ALD) alumina (Al_2O_3) 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 Al_2O_3 films show good dielectric behavior with minimum leakage and capacitance densities of 7.0 nF/cm~2 and 1.034 × 10~7 F/cm~2, 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 Al_2O_3 gate dielectric demonstrates good saturation behavior with saturation current and saturation mobility of 4.16 × 10~4 A and 2.203 cm~2/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 cm~2/Vs. Our study presents the possibility of producing organic-inorganic hybrid low-cost, and high-performance devices for upcoming flexible electronics.