Stretchable Polymer Gate Dielectric by Ultraviolet-Assisted Hafnium Oxide Doping at Low Temperature for High-Performance Indium Gallium Tin Oxide Transistors

Abstract

This paper reports the fabrication of indium gallium tin oxide (IGTO) thin-film transistors (TFTs) with ultraviolet (UV)-treated PVP-co-PMMA-based hybrid gate insulators at an extremely low temperature (≤150 °C). Synergetic hafnia loading and UV treatment were used to tailor the mechanical softness and hydroxyl fraction in the polymer dielectric film. The UV-treated hybrid dielectric film had a low hydroxyl concentration, a smoother surface, and a denser packing nature, which can be explained by the high ionicity of hafnium oxide and photon-assisted improvement in the cohesion between organic and inorganic materials. Suitability of the UV-treated hybrid dielectric film as a gate insulator was evaluated by fabricating bottom gate TFTs with sputtered IGTO films as a channel layer, which showed high carrier mobility at a low temperature. The resulting IGTO TFTs with a UV-treated hybrid gate insulator exhibited a remarkable high field-effect mobility of 25.9 cm2/(V s), a threshold voltage of −0.2 V, a subthreshold gate swing of 0.4 V/decade, and an I ON/OFF ratio of >107 even at a low annealing temperature of 150 °C. The fabricated IGTO TFTs with the UV-treated hybrid dielectric film on the plastic substrate were shown to withstand the 100 times mechanical bending stress even under an extremely small curvature radius of 1 mm due to the intrinsic stretchability of the hybrid dielectric film.

Recent Advances in Metal-Oxide Thin-Film Transistors: Flexible/Stretchable Devices, Integrated Circuits, Biosensors, and Neuromorphic Applications

“…The electrical properties of the device were retained despite the repeated bending tests. [53] with permission from Springer Nature); (b) Image of the IGTO TFTs and their bending test procedure; (c) Transfer characteristics for the IGTO TFTs (adapted from [56] with permission from American Chemical Society); (d) BTS (VGS = ±20 V at 60 • C) time evolution of the threshold voltages for the ε = 0.19% (circle) and 0.93% (square) cases in a vacuum and air ambient; (e) Vth shift after 10,000 s BTS for different strain and ambient conditions (adapted from [57] with permission from Taylor & Francis).…”

“…Hur et al fabricated an indium gallium tin oxide (IGTO) transistor using a H50UV hybrid dielectric film on a PI/Polydimethylsiloxane (PDMS) substrate (Figure 2b,c) [56]. High insulating characteristics of the hybrid gate dielectric films were improved significantly with the reduction of residual hydroxyl groups due to the combination of highly ionic hafnium oxide by a UV treatment.…”

Electrical Performance and Stability Improvements of High-Mobility Indium–Gallium–Tin Oxide Thin-Film Transistors Using an Oxidized Aluminum Capping Layer of Optimal Thickness

“…To date, a variety of AOS TFTs having higher µ FE values than those of the IGZO TFTs have been intensively studied for application in next-generation displays [9][10][11]. Among them, the indium-gallium-tin oxide (IGTO) TFT has recently been attracting special attention as a promising high-mobility AOS TFT, because it exhibits excellent electrical properties even at low annealing temperatures (<200 • C) [12][13][14]. Low temperature processing is exceedingly important for flexible display applications because most plastic substrates have low glass transition temperatures (below 200 • C) [15,16].…”

Inkjet-Printed Top-Gate Thin-Film Transistors Based on InGaSnO Semiconductor Layer with Improved Etching Resistance

“…As a result, the printed InGaSnO semiconductor layer is almost not affected during printing the following gate dielectric layer. Although vacuum-processed InGaSnO films with the advantage of excellent electrical and optical properties has been reported before [19][20][21][22][23][24][25][26], it is for the first time to investigate the chemical corrosivity of inkjet-printed InGaSnO semiconductor films, to the best of our knowledge. in the mixture solvent of 2-methoxyethanol and ethylene glycol with a volume ratio of 1/1.…”