Self-Heating-Effect-Induced Degradation Behaviors in a-InGaZnO Thin-Film Transistors

Hsieh, Tien-Yu; Chang, Ting‐Chang; Chen, Te-Chih; Chen, Yu-Te; Tsai, Ming-Yen; Chu, Ann-Kuo; Chung, Yi‐Chen; Ting, Hung‐Che; Chen, Chia‐Yu

doi:10.1109/led.2012.2223654

Cited by 43 publications

(23 citation statements)

References 13 publications

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“…When the large channel width and/or short channel length TFT is operated at high drain voltage, significant selfheating effect will occur, and channel electrons will be trapped at the IGZO/SiO 2 interface or in SiO 2 bulk through the thermionic-field emission process, resulting in a larger observed threshold voltage. [54][55][56] In addition, from Figure 1(a), note that threshold voltage shifts with a small variation of the slope in the transfer characteristics. This indicates that some shallow sub-conduction band trap states are created at the IGZO active layer/gate dielectric interface during the self-heating-induced trapping process, resulting in a small amount mobility and subthreshold swing degradation.…”

Section: Resultsmentioning

confidence: 89%

“…56 It is well known that the self-heating effect arises in silicon-oninsulator (SOI) MOSFETs and low-temperature-polycrystalline silicon (LTPS) TFTs because the surrounding oxide or other thermal insulating materials make it difficult to dissipate the heat generated in the active layer when high current flows through the channel, a situation quite similar to that found in the IGZO channel layer. 57 In addition, the thermal conductivity of IGZO is much lower than Si and is comparable to SiO 2 .…”

Section: Resultsmentioning

confidence: 99%

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Influence of an anomalous dimension effect on thermal instability in amorphous-InGaZnO thin-film transistors

Liu

Chang

Chou

et al. 2014

Journal of Applied Physics

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This paper investigates abnormal dimension-dependent thermal instability in amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors. Device dimension should theoretically have no effects on threshold voltage, except for in short channel devices. Unlike short channel drain-induced source barrier lowering effect, threshold voltage increases with increasing drain voltage. Furthermore, for devices with either a relatively large channel width or a short channel length, the output drain current decreases instead of saturating with an increase in drain voltage. Moreover, the wider the channel and the shorter the channel length, the larger the threshold voltage and output on-state current degradation that is observed. Because of the surrounding oxide and other thermal insulating material and the low thermal conductivity of the IGZO layer, the self-heating effect will be pronounced in wider/shorter channel length devices and those with a larger operating drain bias. To further clarify the physical mechanism, fast ID-VG and modulated peak/base pulse time ID-VD measurements are utilized to demonstrate the self-heating induced anomalous dimension-dependent threshold voltage variation and on-state current degradation.

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Section: Resultsmentioning

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Influence of an anomalous dimension effect on thermal instability in amorphous-InGaZnO thin-film transistors

Liu

Chang

Chou

et al. 2014

Journal of Applied Physics

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“…effect will introduce threshold voltage shift. [10,15] As is shown in Fig 4, the electrons can gain enough energy to cross the barrier of SiO 2 /IGZO and be trapped into their interface or SiO 2 dielectrics layer due to self-heating effect. Then V TH shift will happen accordingly.…”

Section: Methodsmentioning

confidence: 99%

P‐1.1: Anomalous Dependence of Threshold Voltage on Channel Width and Drain Voltage in Back‐channel‐etched a‐IGZO TFTs

Yang

Zhou

Zhang

2018

Symp Digest of Tech Papers

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The back‐channel‐etched (BCE) amorphous InGaZnO thin‐film transistors with different channel widths (Ws) are fabricated. The performance of VTH depends on both channel width (W) and drain voltage (VD) in this work. It is shown that neither W nor VD can create influence in VTH when W or VD is relatively small. However, when both W and VD are large enough, there will be an anomalous phenomenon that VTH increases with the increasing W or the increasing VD. The self‐heating effect can be used to account for this anomalous dependence of VTH on W and VD.

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“…In the early stage of stress, such feedback-assisted self-heating is weak yet, so that the negative V th shift by hole trapping can be observed, however, in the later stage of stress the feedback-assisted channel heating gets more serious particularly in short channel device so as to cause thermionic electron emission from active to GI, which leads to electron trapping into GI (Fig. 4(c)) [6]- [7]. As a result, the electron trapping overrides the hole trapping effects, switching the negative V th shift to a positive side.…”

Section: Analysis Of Self-heating Effect On Short Channel Amorphous Imentioning

confidence: 99%

“…Self-heating is likely to happen for a-IGZO TFT under such high current operating conditions because the thermal conductivity of the active layer is quite low compared to those of Si devices [3]. Nonetheless, there have not been enough studies to characterize and resolve the self-heating issues in a-IGZO TFTs [4]- [7], and any sufficient explanation and understandings for the self-heating induced degradation of short channel a-IGZO TFTs are particularly in lack.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Self-Heating Effect on Short Channel Amorphous InGaZnO Thin-Film Transistors

Lee

Jeon

Choi

et al. 2015

IEEE Electron Device Lett.

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We report on a TFT degradation encountered in short channel a-IGZO TFTs under high applied power condition leading to self-heating. Negative shift was observed in the initial stage of stress period followed by positive shift with severe degradation. To understand the causes of this phenomenon in depth, trap density-of-states were measured by photo-excited charge-collection spectroscopy and time dependent recovery of stressed device samples was also studied. As a result, we found that the combination of hot carrier effect and self-heating in channel was responsible for the degradation.Index Terms-amorphous InGaZnO (a-IGZO), thin-film transistor, self-heating effect, hot carrier effect, density of states. 0741-3106 (c)

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Self-Heating-Effect-Induced Degradation Behaviors in a-InGaZnO Thin-Film Transistors

Cited by 43 publications

References 13 publications

Influence of an anomalous dimension effect on thermal instability in amorphous-InGaZnO thin-film transistors

Influence of an anomalous dimension effect on thermal instability in amorphous-InGaZnO thin-film transistors

P‐1.1: Anomalous Dependence of Threshold Voltage on Channel Width and Drain Voltage in Back‐channel‐etched a‐IGZO TFTs

Analysis of Self-Heating Effect on Short Channel Amorphous InGaZnO Thin-Film Transistors

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