H2O adsorption on amorphous In-Ga-Zn-O thin-film transistors under negative bias stress

Yang, Jianwen; Liao, Po‐Yung; Chang, Ting‐Chang; Chiang, Hsiao‐Cheng; Chen, Bo-Wei; Chien, Yu‐Chieh; Dong, Lin; Ren, Jinhua; Fu, Ruofan; Qu, Mingyue; Pi, Shubin; Han, Yanbing; Kang, Haoqing; Zhang, Qun

doi:10.1063/1.4999923

Cited by 24 publications

(27 citation statements)

References 20 publications

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“…The stability of a‐IZNO TFTs (Ni content: 6.6 at%) under positive bias stress (PBS, V GS = 20 V) and negative bias stress (NBS, V GS = −20 V) was investigated; the results are shown in Figure a,b, respectively. It can be deduced that no defects were created during the PBS and NBS tests because no SS degradation was observed during these processes . Figure c summarizes the V th shifts (Δ V th ) as a function of bias stress time for a‐IZNO TFTs and undoped IZO TFTs (for comparison).…”

Section: Resultsmentioning

confidence: 95%

High‐Performance Thin‐Film Transistors with Nickel‐Doped Indium Zinc Oxide Channel Layers

Dong

Shao

et al. 2019

Physica Status Solidi (a)

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High‐performance thin‐film transistors (TFTs) with amorphous nickel‐doped indium zinc oxide (a‐IZNO) channel layers are fabricated by radio‐frequency magnetron sputtering. The influence of nickel (Ni)‐doping content on the electrical properties of a‐IZNO TFTs are investigated. With increasing Ni‐doping content, the threshold voltage shifts to the positive direction, which is attributed to the reduction in oxygen vacancies. The a‐IZNO TFTs at Ni content of 6.6 at% exhibit optimum performance, with a field‐effect mobility of 30.2 cm2 V−1 s−1, a threshold voltage of −1.1 V, a subthreshold swing of 0.19 V decade−1, and an on‐to‐off current ratio of 3.7 × 107. In addition, the devices show high stability under positive and negative bias stress. These results suggest that Ni is an effective carrier suppressor for indium zinc oxide (IZO) thin film, making a‐IZNO a promising channel material for TFTs.

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Section: Resultsmentioning

confidence: 95%

High‐Performance Thin‐Film Transistors with Nickel‐Doped Indium Zinc Oxide Channel Layers

Dong

Shao

et al. 2019

Physica Status Solidi (a)

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“…With increasing stress time, no hump was created for TFTs with t ITO values of 3 nm, but the hump was strengthened for TFTs with t ITO values of 9 nm. Under PBS, electrons were trapped in Al 2 O 3 dielectric or/and at the Al 2 O 3 /ZnO interface, which influenced the shielding gate electric field [ 30 , 31 ]. When the t ITO was 3 nm, V ON and V hump increased simultaneously with the stress time, so no hump occurred.…”

Section: Resultsmentioning

confidence: 99%

Structural Engineering Effects on Hump Characteristics of ZnO/InSnO Heterojunction Thin-Film Transistors

Dong

Han

et al. 2022

Nanomaterials

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Transparent conductive oxides (TCO) have been extensively investigated as channel materials for thin-film transistors (TFTs). In this study, highly transparent and conductive InSnO (ITO) and ZnO films were deposited, and their material properties were studied in detail. Meanwhile, we fabricated ZnO/ITO heterojunction TFTs, and explored the effects of channel structures on the hump characteristics of ZnO/ITO TFTs. We found that Vhump–VON was negatively correlated with the thickness of the bottom ZnO layer (10, 20, 30, and 40 nm), while it was positively correlated with the thickness of the top ITO layer (3, 5, 7, and 9 nm), where Vhump is the gate voltage corresponding to the occurrence of the hump and VON is the turn-on voltage. The results demonstrated that carrier transport forms dual current paths through both the ZnO and ITO layers, synthetically determining the hump characteristics of the ZnO/ITO TFTs. Notably, the hump was effectively eliminated by reducing the ITO thickness to no more than 5 nm. Furthermore, the hump characteristics of the ZnO/ITO TFTs under positive gate-bias stress (PBS) were examined. This work broadens the practical application of TCO and provides a promising method for solving the hump phenomenon of oxide TFTs.

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“…Alternatively, it is noteworthy that both VTFTs showed larger Δ V TH during the NBS than the PBS, which is inconsistent with typical behaviors of the conventional IGZO TFTs, because there are few holes to be trapped owing to n-type behaviors of the IGZO semiconductor. Thus, the origin of the negative V TH shift under NBS conditions for the fabricated VTFTs was suggested to be due to the preadsorptions of H + ions and/or H 2 O molecules on the surface of the organic Zeocoat spacer exposed to the atmosphere prior to the deposition of active channel layer. − In other words, positively charged species were trapped in the back-channel region during the device fabrication process, accelerating NBS instability. Nevertheless, the PBS and NBS stabilities of the fabricated flexible VTFTs using an ALD-grown IGZO channel layer were sufficiently comparable to those obtained from the well-fabricated conventional planar-channel IGZO TFTs, which suggests that the robust operational stability could be obtained by properly designed process conditions for the VTFTs.…”

Section: Results and Discussionmentioning

confidence: 99%

Highly Robust Flexible Vertical-Channel Thin-Film Transistors Using Atomic-Layer-Deposited Oxide Channels and Zeocoat Spacers on Ultrathin Polyimide Substrates

Kim

Furuta

Yoon

2019

ACS Appl. Electron. Mater.

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Mechanically flexible vertical-channel-structured thin-film transistors (VTFTs) with a channel length of 200 nm were fabricated on 1.2 μm thick colorless polyimide (CPI) substrates. All layers composing the gate stacks were prepared by atomic-layer deposition (ALD) with a good step coverage, and the process thermal budget was designed below 180 °C. Zeocoat was introduced as a spacer material to improve the device characteristics by properly determining the process conditions for clearly forming the vertical sidewalls. The transfer characteristics of the fabricated flexible ZnO and IGZO VTFTs showed the field-effect mobility of 3.31 and 6.57 cm2 V–1 s–1, the threshold voltages of 2.34 and 1.52 V, the subthreshold swings of 1.42 and 0.34 V/dec, and I ON/I OFF of 1.13 × 104 and 5.16 × 105, respectively, after the postannealing at 150 °C. The threshold voltage shifts (ΔV TH) under positive and negative bias stresses (PBS and NBS) were estimated to be +1.0, +1.8 V and −1.8, −3.8 V for 104 s for ZnO and IGZO VTFTs, respectively. The flexible IGZO VTFTs delaminated by means of a laser lift-off process did not show any marked degradation in device characteristics under mechanically strained conditions at various radii of curvature (R c). The ΔV TH values were also estimated to be +1.2 and −2.1 V under PBS and NBS at R c of 1 mm, respectively, demonstrating stable bending reliability. Appropriate choices of spacer materials, optimization of patterning process for spacer patterns, and ALD process of IGZO active channel can be proposed as key process parameters for guaranteeing excellent device performance of the oxide-channel VTFTs in this work.

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H2O adsorption on amorphous In-Ga-Zn-O thin-film transistors under negative bias stress

Cited by 24 publications

References 20 publications

High‐Performance Thin‐Film Transistors with Nickel‐Doped Indium Zinc Oxide Channel Layers

High‐Performance Thin‐Film Transistors with Nickel‐Doped Indium Zinc Oxide Channel Layers

Structural Engineering Effects on Hump Characteristics of ZnO/InSnO Heterojunction Thin-Film Transistors

Highly Robust Flexible Vertical-Channel Thin-Film Transistors Using Atomic-Layer-Deposited Oxide Channels and Zeocoat Spacers on Ultrathin Polyimide Substrates

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