Low-Temperature, High-Performance InGaZnO Thin-Film Transistors Fabricated by Capacitive Coupled Plasma-Assistant Magnetron Sputtering

Liu, Chang; Sun, Ying; Qin, Houyun; Liu, Yiming; Song, Wei; Zhao, Yi

doi:10.1109/led.2019.2896111

Cited by 23 publications

(10 citation statements)

References 15 publications

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“…This limitation requires the development of new approaches to achieve comparable electrical properties at a relatively low temperature. Several methods have already been proposed (these methods are referred to as “activation process of IGZO”), such as active IGZO layer oxidation at low temperatures by O 2 wet and O 3 annealing [ 15 , 16 ], high-pressure O 2 and N 2 gas annealing [ 17 ], hydrogen injection and oxidation for low-temperature aqueous solution-processed IGZO TFT [ 18 ], microwave and e-beam annealing [ 19 ], capacitive coupled plasma-assistant IGZO magnetron sputtering [ 20 ], and mechanochemical and thermal treatment [ 21 ]. Our research group has recently reported that adding hydrogen to the sputtering atmosphere can effectively reduce the activation temperature of IGZO films [ 22 , 23 , 24 ].…”

Section: Introductionmentioning

confidence: 99%

Defect Passivation and Carrier Reduction Mechanisms in Hydrogen-Doped In-Ga-Zn-O (IGZO:H) Films upon Low-Temperature Annealing for Flexible Device Applications

2022

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Low-temperature activation of oxide semiconductor materials such as In-Ga-Zn-O (IGZO) is a key approach for their utilization in flexible devices. We previously reported that the activation temperature can be reduced to 150 °C by hydrogen-doped IGZO (IGZO:H), demonstrating a strong potential of this approach. In this paper, we investigated the mechanism for reducing the activation temperature of the IGZO:H films. In situ Hall measurements revealed that oxygen diffusion from annealing ambient into the conventional Ar/O2-sputtered IGZO film was observed at >240 °C. Moreover, the temperature at which the oxygen diffusion starts into the film significantly decreased to 100 °C for the IGZO:H film deposited at hydrogen gas flow ratio (R[H2]) of 8%. Hard X-ray photoelectron spectroscopy indicated that the near Fermi level (EF) defects in the IGZO:H film after the 150 °C annealing decreased in comparison to that in the conventional IGZO film after 300 °C annealing. The oxygen diffusion into the film during annealing plays an important role for reducing oxygen vacancies and subgap states especially for near EF. X-ray reflectometry analysis revealed that the film density of the IGZO:H decreased with an increase in R[H2] which would be the possible cause for facilitating the O diffusion at low temperature.

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Section: Introductionmentioning

confidence: 99%

Defect Passivation and Carrier Reduction Mechanisms in Hydrogen-Doped In-Ga-Zn-O (IGZO:H) Films upon Low-Temperature Annealing for Flexible Device Applications

2022

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“…Conversely, excellent switching characteristics were observed for IGTO TFTs with an Al 2 O 3 dielectric grown at P O2 = 5.0%, exhibiting a high μ FE of 58.8 cm 2 /Vs, SS of 0.12 V/decade, V TH of 0.5 V, and I ON/OFF ratio > 10 9 , as shown in Figure c and Table . This performance exceeds that of state-of-the-art a -IGZO TFTs that are currently being used in AMOLED TV products, as well as all previously reported AOS TFTs fabricated at low temperatures (<200 °C). − The reasons for this remarkable performance will be discussed later. However, the μ FE value of IGTO TFTs decreased with an increase of P O2 from 5.0% to 20%, which was accompanied by a positively displaced V TH .…”

Section: Resultsmentioning

confidence: 85%

High-Performance Indium Gallium Tin Oxide Transistors with an Al₂O₃ Gate Insulator Deposited by Atomic Layer Deposition at a Low Temperature of 150 °C: Roles of Hydrogen and Excess Oxygen in the Al₂O₃ Dielectric Film

Choi

Kim

Ueda

et al. 2021

ACS Appl. Mater. Interfaces

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In this work, high-performance amorphous In0.75Ga0.23Sn0.02O (a-IGTO) transistors with an atomic layer-deposited Al2O3 dielectric layer were fabricated at a maximum processing temperature of 150 °C. Hydrogen (H) and excess oxygen (Oi) in the Al2O3 film, which was controlled by adjusting the oxygen radical density (PO2: flow rate of O2/[Ar+O2]) in the radio-frequency (rf) plasma during ALD growth of Al2O3, significantly affected the performance and stability of the resulting IGTO transistors. The concentrations of H and Oi in Al2O3/IGTO stacks according to PO2 were characterized by secondary ion mass spectroscopy, X-ray photoelectron spectroscopy, hard X-ray photoemission spectroscopy, and thermal desorption spectroscopy. The high concentration of H at a low PO2 of 2.5% caused heavy electron doping in the underlying IGTO during thermal annealing at 150 °C, leading to a conductive behavior in the resulting transistor without modulation capability. In contrast, a high PO2 condition of 20% introduced O2 molecules (or Oi) into the Al2O3 film, which negatively impacted the carrier mobility and caused anomalous photo-bias instability in the IGTO transistor. Through in-depth understanding of how to manipulate H and Oi in Al2O3 by controlling the PO2, we fabricated high-performance IGTO transistors with a high field-effect mobility (μFE) of 58.8 cm2/Vs, subthreshold gate swing (SS) of 0.12 V/decade, threshold voltage (V TH) of 0.5 V, and I ON/OFF ratio of ∼109 even at the maximum processing temperature of 150 °C. Simultaneously, the optimized devices were resistant to exposure to external positive gate bias stress (PBS) and negative bias stress (NBS) for 3600 s, where the V TH shifts for exposure to PBS and NBS for this duration were 0.1 V and −0.15 V, respectively.

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“…[ 1–4 ] However, new emerging industries, such as 5G, artificial intelligence, and virtual reality, require high‐resolution and fast‐response displays, which in turn require thin‐film transistors (TFTs) with high mobility. These goals can be achieved by using element doping, [ 5 ] plasma treatment, [ 2 ] and metal‐capping layers. [ 6–8 ] However, the formation of a bilayer structure is the simplest way to achieve these goals, i.e., using a very thin semiconductor with a high carrier concentration that is stacked with a low‐mobility but stable AOS layer to obtain high‐mobility and high‐stability TFTs.…”

Section: Introductionmentioning

confidence: 99%

Critical Assessment of the High Carrier Mobility of Bilayer In₂O₃/IGZO Transistors and the Underlying Mechanisms

Guo

Xie

et al. 2023

Adv Elect Materials

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High‐performance bilayer In2O3/IGZO thin‐film transistors (TFTs) fabricated by pulsed laser deposition are reported. The TFTs exhibit an on/off current ratio of 109, a reversed subthreshold slope (ss) of 0.08 V dec−1, and a high saturation mobility of 47.9 cm2 V−1 s−1. The reliability of the mobility values is critically validated and assessed by four‐probe measurements, the transfer‐length method, and the temperature‐dependence. X‐ray photoelectron spectra are combined with C–V measurements to characterize the interface, and the results show that a two‐dimensional electron gas (2DEG)‐like state accumulates at the In2O3/IGZO interface. However, this state only forms in the subthreshold region and does not cause the high carrier mobility in the region above the threshold. Instead, the enhanced carrier mobility results from the intrinsic high mobility of the In2O3, the smooth surface, and the low‐defect states in the In2O3/IGZO bilayer with a good percolation transport path.

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Low-Temperature, High-Performance InGaZnO Thin-Film Transistors Fabricated by Capacitive Coupled Plasma-Assistant Magnetron Sputtering

Cited by 23 publications

References 15 publications

Defect Passivation and Carrier Reduction Mechanisms in Hydrogen-Doped In-Ga-Zn-O (IGZO:H) Films upon Low-Temperature Annealing for Flexible Device Applications

Defect Passivation and Carrier Reduction Mechanisms in Hydrogen-Doped In-Ga-Zn-O (IGZO:H) Films upon Low-Temperature Annealing for Flexible Device Applications

High-Performance Indium Gallium Tin Oxide Transistors with an Al₂O₃ Gate Insulator Deposited by Atomic Layer Deposition at a Low Temperature of 150 °C: Roles of Hydrogen and Excess Oxygen in the Al₂O₃ Dielectric Film

Critical Assessment of the High Carrier Mobility of Bilayer In₂O₃/IGZO Transistors and the Underlying Mechanisms

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Low-Temperature, High-Performance InGaZnO Thin-Film Transistors Fabricated by Capacitive Coupled Plasma-Assistant Magnetron Sputtering

Cited by 23 publications

References 15 publications

Defect Passivation and Carrier Reduction Mechanisms in Hydrogen-Doped In-Ga-Zn-O (IGZO:H) Films upon Low-Temperature Annealing for Flexible Device Applications

Defect Passivation and Carrier Reduction Mechanisms in Hydrogen-Doped In-Ga-Zn-O (IGZO:H) Films upon Low-Temperature Annealing for Flexible Device Applications

High-Performance Indium Gallium Tin Oxide Transistors with an Al2O3 Gate Insulator Deposited by Atomic Layer Deposition at a Low Temperature of 150 °C: Roles of Hydrogen and Excess Oxygen in the Al2O3 Dielectric Film

Critical Assessment of the High Carrier Mobility of Bilayer In2O3/IGZO Transistors and the Underlying Mechanisms

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High-Performance Indium Gallium Tin Oxide Transistors with an Al₂O₃ Gate Insulator Deposited by Atomic Layer Deposition at a Low Temperature of 150 °C: Roles of Hydrogen and Excess Oxygen in the Al₂O₃ Dielectric Film

Critical Assessment of the High Carrier Mobility of Bilayer In₂O₃/IGZO Transistors and the Underlying Mechanisms