Investigation of a Hump Phenomenon in Back-Channel-Etched Amorphous In-Ga-Zn-O Thin-Film Transistors Under Negative Bias Stress

Yang, Jianwen; Liao, Po‐Yung; Chang, Ting‐Chang; Chen, Bo-Wei; Huang, Hui‐Chun; Chiang, Hsiao‐Cheng; Su, Wan-Ching; Zhang, Qun

doi:10.1109/led.2017.2686898

Cited by 20 publications

(11 citation statements)

References 19 publications

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“…Further R O 2 increase to 80% leads to the development of a hump in the transfer curves. This hump is ascribed to the presence of two channels: an additional parasitic channel with lower V on can appear at the edges of the IGZO island . In our case, the a-IGZO sample with R O 2 = 80% was sputtered with an excess of oxygen.…”

Section: Resultsmentioning

confidence: 86%

Systematic Study on the Amorphous, C-Axis-Aligned Crystalline, and Protocrystalline Phases in In–Ga–Zn Oxide Thin-Film Transistors

Glushkova

Dekkers

Nag

et al. 2021

ACS Appl. Electron. Mater.

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In an effort to fabricate In–Ga–Zn oxide (IGZO) thin-film transistors (TFTs) that combine high performance and high stability, we optimize sputtering conditions to create devices based on different IGZO phases: amorphous, c-axis-aligned crystalline (CAAC), and a transition between them, which is introduced here as protocrystalline IGZO. For this, we study the performance of TFTs based on thin films of IGZO sputtered at different substrate temperatures T sub and oxygen flow ratios R O2 . While T sub is the principal phase-determining parameter, R O2 can be further optimized to enhance IGZO TFT characteristics. For both amorphous IGZO and CAAC IGZO, the best TFT performance and the best TFT bias stress stability are found under different sputtering conditions. In contrast, the protocrystalline IGZO shows a convergence of the highest TFT performance and the best bias stress stability, observed for an IGZO film sputtered at T sub = 200 °C and R O2 = 20%.

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Section: Resultsmentioning

confidence: 86%

Systematic Study on the Amorphous, C-Axis-Aligned Crystalline, and Protocrystalline Phases in In–Ga–Zn Oxide Thin-Film Transistors

Glushkova

Dekkers

Nag

et al. 2021

ACS Appl. Electron. Mater.

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“…Additionally, with the assistance of large E y induced by PBS, the MO bonds may be broken down and additional V O s may be introduced, bringing the increase of the free carrier concentration and further making the device turned on early. [ 74–78 ]…”

Section: Mechanism Discussionmentioning

confidence: 99%

Effect of Moisture Exchange Caused by Low‐Temperature Annealing on Device Characteristics and Instability in InSnZnO Thin‐Film Transistors

Chen

Zhang

Deng

et al. 2022

Adv Materials Inter

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Thin‐film transistors (TFTs) in practical operations are inevitably impacted by moisture and temperature. An investigation on the joint effect of environmental moisture and working temperature on device characteristics and instability is becoming necessary. However, few related studies have been performed. In this work, a low‐temperature (LT) annealing in air is proposed to simulate the working conditions of TFTs in display applications. The effect of moisture exchange caused by LT annealing on device characteristics and instability of InSnZnO (ITZO) TFTs is systematically investigated. Combined with X‐ray photoelectron spectroscopy analysis, TCAD design simulation, and the measurement of relative humidity (RH) change on the device surface, a model considering water diffusion and water ionization is proposed. The negative shift of the transfer curve is attributed to the extra electrons released from the water ionization and the positive‐bias‐stress‐induced instability is mainly attributed to the generation of interstitial/substitutional hydrogens and aggregation of hydrogen ions at the backchannel. The temperature and the RH on the device surface jointly determine the moisture diffusion direction. Furthermore, the model is verified by an LT vacuum annealing. The results and the model will be beneficial for the further reliable design of ITZO TFTs in commercial applications.

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“…As a crucial issue to be solved, the hump phenomenon emerging in transfer curves negatively shifts the turn-on voltage (V ON ) of the oxide TFTs, which not only adversely affects pixel brightness but also increases the power consumption of the displays [ 10 ]. The hump phenomenon has been widely examined for the single-channel oxide TFTs [ 11 , 12 , 13 , 14 ].…”

Section: Introductionmentioning

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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Investigation of a Hump Phenomenon in Back-Channel-Etched Amorphous In-Ga-Zn-O Thin-Film Transistors Under Negative Bias Stress

Cited by 20 publications

References 19 publications

Systematic Study on the Amorphous, C-Axis-Aligned Crystalline, and Protocrystalline Phases in In–Ga–Zn Oxide Thin-Film Transistors

Systematic Study on the Amorphous, C-Axis-Aligned Crystalline, and Protocrystalline Phases in In–Ga–Zn Oxide Thin-Film Transistors

Effect of Moisture Exchange Caused by Low‐Temperature Annealing on Device Characteristics and Instability in InSnZnO Thin‐Film Transistors

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

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