Recent advances in low-temperature solution-processed oxide backplanes

Heo, Seon-Hee; Yoon, Dae Ho; Jung, Tae Soo; Kim, Hyun Jae

doi:10.1080/15980316.2013.806274

Cited by 46 publications

(27 citation statements)

References 20 publications

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“…Amorphous oxide semiconductor based thin film transistors (AOS TFTs) have attracted much attention for the active matrix back plane of next generation displays. AOS TFTs are of particular interest for flexible, wearable, and foldable devices . Their many advantages include high transparency in the visible light region, high flexibility, and relatively low processing temperatures compared with polycrystalline Si TFTs .…”

Section: Introductionmentioning

confidence: 99%

Modified Stoichiometry in Homogeneous Indium–Zinc Oxide System as Vertically Graded Oxygen Deficiencies by Controlling Redox Reactions

Tak

Rim

Yoon

et al. 2015

Adv Materials Inter

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several issues such as reliability and device performance. [ 4 ] To solve these problems, research has focused on material engineering, [ 5 ] post treatment engineering, [ 6,7 ] and structural engineering [ 8,9 ] approaches. However, the optimal structure for AOS TFTs has not been established, whereas amorphous and polycrystalline Si TFTs are generally manufactured with bottom-and top-gate structures, respectively.In AOS TFTs with a top-gate structure, the back-channel is not exposed to the environment because the gate dielectric acts as a passivation layer that prevents interaction with ambient gases. [ 10 ] Furthermore, the top-gate structure effectively reduces resistance-capacitance (RC) delay by decreasing overlap of the source/drain and gate electrodes via a self-alignment process. [ 11 ] Hence, the top-gate structure has also been suggested for the AOS TFT back-plane technology for high resolution and large displays. However, the top-gate structure is relatively diffi cult to manufacture using current production lines that use conventional fabrication processes designed for amorphous Si TFTs; many process steps are required. Although AOS TFTs with a bottom-gate structure could be manufactured more easily with existing processes, an additional etch stopper layer must be deposited to prevent chemical damage from occurring during the metal etching process, when the back-channel etch structure is employed. [ 12 ] Furthermore, a true passivation layer is needed because of the exposure of the back-channel to the external environment, [ 12,13 ] and the overlap between the source/ drain and gate electrodes causes poor device performance. [ 14 ] For these reasons, a hetero multi-stacked structure has recently been suggested. [ 8,9 ] This structure could improve the electrical characteristics and enable self passivation, without an additional passivation layer, by depositing channel material repeatedly during channel layer fabrication. In a hetero multi-stack structure, the front-channel has high conductivity and the backchannel has low conductivity because each layer leads to a moderate current fl ow and self passivation, respectively. However, a hetero multi-stack structure has several issues: the presence of interfaces in the middle of the channel layer, complicated diffusion effects among the channel layers, and high fabrication cost because of the need to use several depositions of rare materialsThe present study suggests a way to improve electrical characteristics and stabilities by forming a different stoichiometry in a homogeneous system without using a multiple deposition process. Post treatment by sequential pressure annealing (SPA) of a homogeneous indium-zinc oxide system is carried out to fabricate vertically graded oxygen defi ciencies via redox reactions. The SPA treatment consists of several steps. First, hydrogen pressure annealing is performed to chemically expedite the reduction reaction of weak chemical bonds in the overall channel region and thereby make the material highly conducting. Second, o...

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Section: Introductionmentioning

confidence: 99%

Modified Stoichiometry in Homogeneous Indium–Zinc Oxide System as Vertically Graded Oxygen Deficiencies by Controlling Redox Reactions

Tak

Rim

Yoon

et al. 2015

Adv Materials Inter

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“…1 Introduction Indium-gallium-zinc oxide (IGZO) is the archetypal transparent oxide semiconductor for thin film transistors (TFTs) and has recently received considerable attention [1]. IGZO thin films have been elaborated by conventional techniques (sputtering, pulsed laser deposition) and more recently by solution-based process like solgel [2].…”

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Local structure around Zn and Ga in solution‐processed In–Ga–Zn–O and implications for electronic properties

Revenant

Benwadih

Proux

2015

Physica Rapid Research Ltrs

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International audienceWe study by X-ray absorption spectroscopy the local structure around Zn and Ga in solution-processed In-Ga-Zn-O thin films as a function of thermal annealing. Zn and Ga environments are amorphous up to 450 degrees C. At 200 degrees C and 450 degrees C, the Ga atoms are in a beta-Ga2O3 like structure, mostly tetrahedral gallium oxide phase. Above 300 degrees C, the Zn atoms are in a tetrahedral ZnO phase for atoms inside the nanoclusters. The observed formation of the inorganic structure above 300 degrees C may be correlated to the rise of the mobility for IGZO TFTs. The Zn atoms localized at the nanocluster boundary are undercoordinated with O. Such ZnO cluster boundary could be responsible for electronic defect levels. Such defect levels were put in evidence in the upper half of the band gap. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

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“…This is because the oxide TFT has many advantages, such as high transparency in visible regions, lower off-currents, and an unnecessary ohmic layer compared to Si-based TFTs [2,3]. For these reasons, only short-time (about-8-year) Organic lightemitting diode (OLED) and LCD display panels have been manufactured using IGZO TFTs.…”

Section: Introductionmentioning

confidence: 99%

Reduction of activation temperature at 150°C for IGZO films with improved electrical performance via UV-thermal treatment

Tak

Park

Jung

et al. 2016

Journal of Information Display

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Activation using the simultaneous UV-thermal (U-T) treatment of sputter-processed InGaZnO (IGZO) thin-film transistors (TFTs) is suggested. This treatment was performed to lower the activation temperature from 300°C (thermal activation alone) to 150°C as well as to improve the electrical characteristics and stability. Despite the low temperature, the U-T-treated devices showed superior electrical characteristics and stability compared to the devices that were only thermally activated (300°C): the mobility improved from 5.19 ± 1.8 to 16.20 ± 1.5 cm 2 /Vs, the on-off ratio increased from (5.58 ± 3.21) × 10 8 to (2.50 ± 2.23) × 10 9 , and the threshold voltage shift (under positive bias stress for 1000 s) decreased from 7.1 to 2.2 V. These improvements are attributed to the following two contributions: (1) generation of reactive oxygen radical at a low temperature and (2) decomposition-rearrangement of the metal oxide (MO) bonds in the IGZO active layer. Contributions (1) and (2) effectively increased the MO bonds and decreased the defect-site-related oxygen vacancies. ARTICLE HISTORY

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Recent advances in low-temperature solution-processed oxide backplanes

Cited by 46 publications

References 20 publications

Modified Stoichiometry in Homogeneous Indium–Zinc Oxide System as Vertically Graded Oxygen Deficiencies by Controlling Redox Reactions

Modified Stoichiometry in Homogeneous Indium–Zinc Oxide System as Vertically Graded Oxygen Deficiencies by Controlling Redox Reactions

Local structure around Zn and Ga in solution‐processed In–Ga–Zn–O and implications for electronic properties

Reduction of activation temperature at 150°C for IGZO films with improved electrical performance via UV-thermal treatment

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