Unintended Carbon-Related Impurity and Negative Bias Instability in High-Mobility Oxide TFTs

Shiah, Yu‐Shien; Sim, Kihyung; Ueda, Shigenori; Kim, Junghwan; Hosono, Hideo

doi:10.1109/led.2021.3101654

Cited by 39 publications

(22 citation statements)

References 17 publications

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“…Later, this concept was successfully implemented, demonstrating the strong potential of using AOS with mobility of 10 cm 2 /Vs as an alternative to hydrogenated amorphous silicon (a:Si–H), the mobility of which does not exceed 1 cm 2 /Vs [ 2 ]. These results inspired subsequent research and development of AOS such as InGaZnO (IGZO), InGaO (IGO), GaZnO (GZO), InZnO (IZO), InSnZnO (ITZO), ZnSnO (ZTO) and others for various applications [ 3 , 4 , 5 ]. These materials possess key advantages, including high electron mobility (>10 cm 2 /Vs) and high transparency, suitability for low-temperature processes which enable it to be used in flexible and transparent electronics, and industrial friendly scalability due to high uniformity and large area deposition at room temperature [ 6 , 7 , 8 ].…”

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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“…The incorporation of the carrier suppressor, Y, helped bias stability by reducing O V density in the SnO 2 layer and at the interfaces between the SnO 2 semiconductors and dielectric layers. CO-related impurities also can affect the bias stability of the metal–oxide TFTs. , Figure S5 shows the C 1s XPS spectra as a function of the Y 2 O 3 annealing time. Y 2 O 3 -passivated films show fewer CO-related impurities.…”

Section: Resultsmentioning

confidence: 99%

“…CO-related impurities also can affect the bias stability of the metal−oxide TFTs. 43,44 annealing process above 400 °C. In this experiment, the annealing temperature for Y 2 O 3 films is 300 °C, which is not enough to eliminate fully the CO-related impurities.…”

Section: Introductionmentioning

confidence: 99%

Environmentally and Electrically Stable Sol–Gel-Deposited SnO₂ Thin-Film Transistors with Controlled Passivation Layer Diffusion Penetration Depth That Minimizes Mobility Degradation

Lee

Kim

et al. 2022

ACS Appl. Mater. Interfaces

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This study examines the effect of the annealing time of the Y 2 O 3 passivation layer on the electrical performances and bias stabilities of sol−geldeposited SnO 2 thin-film transistors (TFTs). The environmental stabilities of SnO 2 TFTs were examined. After optimizing the Y 2 O 3 passivation layers in SnO 2 TFTs, the field-effect mobility was 7.59 cm 2 /V•s, the V TH was 9.16 V, the subthreshold swing (SS) was 0.88 V/decade, and the on/off-current ratio was approximately 1 × 10 8 . V TH shifts were only −0.18 and +0.06 V under negative and positive bias stresses, respectively. The SnO 2 channel layer thickness and oxygenvacancy concentration in SnO 2 , which determine the carrier concentration, were successfully tuned by controlling the annealing time of the Y 2 O 3 passivation layers. An extremely thin Y 2 O 3 passivation layer effectively blocked external molecules, thus affecting the device performance. The electrical performance was maximized in SnO 2 TFTs using a 15 min-annealed Y 2 O 3 passivation layer. In this TFT, the field-effect mobility was maximally retained and the bias and environmental stabilities were sustained over 90 days of air exposure.

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“…The optimization of AOS composition is one approach for improving μ FE ; for example, an increase in the In ratio due the considerable spatial spread of the In 5 s orbital with a large overlap can provide a facile electron transport path with a low electron effective mass [ 14 , 15 ]. Although various compositions, including In–Sn–Zn–O [ 16 , 17 ], In–W–Zn–O [ 18 , 19 ], Al–In–Sn–Zn–O [ 20 ], and In–Ga–Zn–Sn–O [ 21 ], have been proposed to enhance the μ FE , the value remains insufficiently high to compete with that of low-temperature polysilicon (LTPS) TFTs [ 22 ].…”

Section: Introductionmentioning

confidence: 99%

Influence of Grain Boundary Scattering on the Field-Effect Mobility of Solid-Phase Crystallized Hydrogenated Polycrystalline In2O3 (In2O3:H)

et al. 2022

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Hydrogenated polycrystalline In2O3 (In2O3:H) thin-film transistors (TFTs) fabricated via the low-temperature solid-phase crystallization (SPC) process with a field-effect mobility (μFE) exceeding 100 cm2 V−1 s−1 are promising candidates for future electronics applications. In this study, we investigated the effects of the SPC temperature of Ar + O2 + H2-sputtered In2O3:H films on the electron transport properties of In2O3:H TFTs. The In2O3:H TFT with an SPC temperature of 300 °C exhibited the best performance, having the largest µFE of 139.2 cm2 V−1 s−1. In contrast, the µFE was slightly degraded with increasing SPC temperature (400 °C and higher). Extended X-ray absorption fine structure analysis revealed that the medium-range ordering in the In2O3:H network was further improved by annealing up to 600 °C, while a large amount of H2O was desorbed from the In2O3:H films at SPC temperatures above 400 °C, resulting in the creation of defects at grain boundaries. The threshold temperature of H2O desorption corresponded well with the carrier transport properties; the µFE of the TFTs started to deteriorate at SPC temperatures of 400 °C and higher. Thus, it was suggested that the hydrogen remaining in the film after SPC plays an important role in the passivation of electron traps, especially for grain boundaries, resulting in an enhancement of the µFE of In2O3:H TFTs.

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Unintended Carbon-Related Impurity and Negative Bias Instability in High-Mobility Oxide TFTs

Cited by 39 publications

References 17 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

Environmentally and Electrically Stable Sol–Gel-Deposited SnO₂ Thin-Film Transistors with Controlled Passivation Layer Diffusion Penetration Depth That Minimizes Mobility Degradation

Influence of Grain Boundary Scattering on the Field-Effect Mobility of Solid-Phase Crystallized Hydrogenated Polycrystalline In2O3 (In2O3:H)

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Unintended Carbon-Related Impurity and Negative Bias Instability in High-Mobility Oxide TFTs

Cited by 39 publications

References 17 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

Environmentally and Electrically Stable Sol–Gel-Deposited SnO2 Thin-Film Transistors with Controlled Passivation Layer Diffusion Penetration Depth That Minimizes Mobility Degradation

Influence of Grain Boundary Scattering on the Field-Effect Mobility of Solid-Phase Crystallized Hydrogenated Polycrystalline In2O3 (In2O3:H)

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Environmentally and Electrically Stable Sol–Gel-Deposited SnO₂ Thin-Film Transistors with Controlled Passivation Layer Diffusion Penetration Depth That Minimizes Mobility Degradation