Inkjet‐Printed and Deep‐UV‐Annealed YAlO_x Dielectrics for High‐Performance IGZO Thin‐Film Transistors on Flexible Substrates

Abstract

stability when compared to their counterparts. [4] Currently existing technologies for commercial applications of TFTs use vacuum-based deposition methods and photolithographic patterning of the layers to ensure a high manufacturing yield.Due to the availability of inexpensive precursors, ease of fabrication, and applicability for large-area processing, solutionprocessed methods may offer low-cost routes for the manufacturing of oxidebased TFTs. [5] Specifically, printing offers an advantage by eliminating the necessity of photolithographic patterning of the deposited layers. However, there are still several challenges before the realization of flexible electronics based on printed oxides, and one of them is the requirement of a hightemperature post deposition annealing (PDA) of the printed layers. [6] To reduce the PDA temperature of the solution-processed layers, several methods such as deep ultraviolet (DUV) annealing, [7][8][9] flash lamp annealing, [10,11] microwave annealing, [12] and solution combustion synthesis [13][14][15][16] have been proposed for semiconductor, conductor, and dielectric layers. DUV annealing (annealing method in this study) is based on the absorption of the deep UV light (λ < 260 nm) by the precursors used in the solution-processed deposition resulting in their decomposition into active oxide layers. DUV has been demonstrated to be applicable not only to oxide dielectrics but also to the semiconductors such as indium oxide, IGZO, and indium zinc oxide. [8] As a major component of the TFT, the dielectric layer is crucial for achieving high-performance devices. The effective polarization of charges in the dielectric under the applied gate bias directly affects the amount of charges accumulated/ depleted in the channel material, which in turn indicates the switching performance of the transistor. Up to now, the majority of low-temperature solution-processed dielectric layers have been reported using spin coating methods, aiming at uniform and pinhole-free layers. [17] Several binary oxide dielectrics with high dielectric constants (high-κ) such as AlO x , YO x , HfO x , and ZrO x have been investigated for their use in oxide TFTs, and the devices with higher mobilities and lower threshold voltages rather than the devices employing SiO 2 insulators Recent developments in inkjet printing have proven it a viable method for low-cost and large-area coating of oxide materials. The main drawback of this method is the common requirement of a post-deposition annealing (PDA) of the printed layers at relatively high temperatures (T > 200 °C). This sets a requirement for the substrate to have high glass transition temperature (T g ). Toreduce the PDA temperature, deep-ultraviolet (DUV) annealing is proposed as an effective method. In this study, yttrium aluminum oxide (YAlO x ) dielectrics are realized for application in flexible electronic devices via inkjet printing and DUV annealing at a temperature of 150 °C. The effect of the Y concentration on the electrical properties of the dielectrics is i...

Recent Progress in Photonic Processing of Metal‐Oxide Transistors

“…Regarding dielectric materials, the most prominent examples are found to be Al 2 O 3 and ZrO x and their derivatives (ZrAlO x or YAlO x ) as well as HfO x and SiO 2 . On the other hand, the pool of conductive materials mostly contains indium‐doped tin oxide (ITO), antimony doped SnO 2 or nanoparticle layers based on Ag .…”

“…The studies discussed in the following section focus on the simultaneous use of DUV and thermal annealing . While the annealing temperature is typically <200 °C, there are some exceptions where higher temperatures were reached .…”

“…The resulting multilayers exhibited improved characteristics yielding low operating voltage TFTs with a maximum electron mobility of 43.9 cm 2 V −1 s −1 . A similar approach was successfully employed to create ink‐jet printed yttrium aluminum oxide dielectrics by Bolat et al…”

Digital and Analog Switching Characteristics of InGaZnO Memristor Depending on Top Electrode Material for Neuromorphic System

“…InGaZnO (IGZO) has been widely used in display and flexible electronics thanks to the advantages of high mobility, uniformity, transparency, and low-temperature processing [34][35][36][37][38][39][40]. In particular, IGZO devices have been recently studied in applications such as wearable healthcare and biosensor, where energy-efficient and flexible logic and memory technologies are needed to process a huge amount of bio-electrical information [41][42][43].…”

A Low-Temperature Solution-Process High-k Dielectric for High-Performance Flexible Organic Field-Effect Transistors

“…Among different material deposition methods, the solution processing of high-k dielectrics by the sol-gel method is promising for its low-cost, being vacuum-free, and compatibility with industrial processing technologies such as spin coating, dip coating, inkjet printing, and roll-to-roll fabrication (Quah et al, 2010;Wang et al, 2013;Wang et al, 2014;Park et al, 2015;McKerricher et al, 2017;Quah et al, 2017;Heo et al, 2018;Jo et al, 2018;Xia et al, 2018;Bolot et al, 2019;Sun et al, 2019). In addition, the solution formed a densely packed thin film with atomic flat-surface roughness, thus facilitating good charge transport in organic semiconductors when deposited onto the dielectric layer, leading to high carrier mobility and low leakage current.…”