Analysis of Instability Mechanism under Simultaneous Positive Gate and Drain Bias Stress in Self-Aligned Top-Gate Amorphous Indium-Zinc-Oxide Thin-Film Transistors

Kim, Jong-Hwa; Choi, Sungju; Jang, Jaeman; Jang, Jun Tae; Kim, Jungmok; Choi, Sung-Jin; Kim, Dong Myong; Kim, Dae Hwan

doi:10.5573/jsts.2015.15.5.526

Cited by 5 publications

(3 citation statements)

References 15 publications

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“…), and that the amount of ionization is greater than the amount of electron trapping. Under the PBS, the drain current reached 300 µA which induces sufficient joule heating to raise the local temperature of the a-IGZO channel, inducing the activation of shallow donor states (oxygen vacancies) [29][30][31]. Therefore, while electron trapping and oxygen vacancy ionization induce positive and negative V th shifts, respectively, the oxygen vacancy ionization was more dominant than electron trapping under the PBS condition with the high drain current, resulting in a negative V th shift [32,33].…”

Section: Resultsmentioning

confidence: 99%

Bi-directional threshold voltage shift of amorphous InGaZnO thin film transistors under alternating bias stress

Kim,

et al. 2024

Semicond. Sci. Technol.

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Amorphous InGaZnO (a-IGZO) has attracted a lot of attention as a high-mobility channel material for thin film transistors (TFTs). However, the instability mechanism involving threshold voltage and subthreshold swing in a-IGZO TFTs still requires further investigation. In this study, we investigated the electrical instability of amorphous InGaZnO thin film transistors subjected to alternating positive and negative bias stresses. Based on the respective mechanisms under positive and negative bias stresses, including ionization and spatial movement of oxygen vacancies, bi-directional threshold voltage shifts were observed under alternating bias stress. The subthreshold swing values vary with the bias stress polarity, reflecting the presence and distribution of oxygen vacancies. Our findings reveal a complementary mechanism based on oxygen vacancies, elucidating the behavior under complex bias stress schemes and extending our understanding of instability mechanisms beyond monotonous bias stress.

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Section: Resultsmentioning

confidence: 99%

Bi-directional threshold voltage shift of amorphous InGaZnO thin film transistors under alternating bias stress

Kim,

et al. 2024

Semicond. Sci. Technol.

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“…For the reliable incorporation of a-IGZO TFTs into the driving circuits for display application, it is crucial to understand the degradation mechanisms of the device under bias stresses. Many research groups have reported stress-induced instability characteristics [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. Most of these studies have focused on the verification of degradation mechanisms, such as charge trapping, hole trapping, and donor-state creation.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Threshold Voltage Shift for Full VGS/VDS/Oxygen-Content Span under Positive Bias Stress in Bottom-Gate Amorphous InGaZnO Thin-Film Transistors

et al. 2021

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In this study, we analyzed the threshold voltage shift characteristics of bottom-gate amorphous indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) under a wide range of positive stress voltages. We investigated four mechanisms: electron trapping at the gate insulator layer by a vertical electric field, electron trapping at the drain-side GI layer by hot-carrier injection, hole trapping at the source-side etch-stop layer by impact ionization, and donor-like state creation in the drain-side IGZO layer by a lateral electric field. To accurately analyze each mechanism, the local threshold voltages of the source and drain sides were measured by forward and reverse read-out. By using contour maps of the threshold voltage shift, we investigated which mechanism was dominant in various gate and drain stress voltage pairs. In addition, we investigated the effect of the oxygen content of the IGZO layer on the positive stress-induced threshold voltage shift. For oxygen-rich devices and oxygen-poor devices, the threshold voltage shift as well as the change in the density of states were analyzed.

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“…It is necessary to predict the circuit operation in alternating current (AC) driving conditions through simulations that reflect analysis results. Until now, there has been much research on direct current (DC) stress [9][10][11][12][13][14][15][16][17], even though most circuits are driven in AC conditions. Hence, it is very important to analyze the instability characteristics of IGZO devices and circuits in various AC conditions so that compact modeling can be drawn for the reliability-aware SPICE (Simulation Program with Integrated Circuit Emphasis) simulation.…”

Section: Introductionmentioning

confidence: 99%

Reliability-Aware SPICE Compatible Compact Modeling of IGZO Inverters on a Flexible Substrate

et al. 2021

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Accurate circuit simulation reflecting physical and electrical stress is of importance in indium gallium zinc oxide (IGZO)-based flexible electronics. In particular, appropriate modeling of threshold voltage (VT) changes in different bias and bending conditions is required for reliability-aware simulation in both device and circuit levels. Here, we present SPICE compatible compact modeling of IGZO transistors and inverters having an atomic layer deposition (ALD) Al2O3 gate insulator on a polyethylene terephthalate (PET) substrate. Specifically, the modeling was performed to predict the behavior of the circuit using stretched exponential function (SEF) in a bending radius of 10 mm and operating voltages ranging between 4 and 8 V. The simulation results of the IGZO circuits matched well with the measured values in various operating conditions. It is expected that the proposed method can be applied to process improvement or circuit design by predicting the direct current (DC) and alternating current (AC) responses of flexible IGZO circuits.

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Analysis of Instability Mechanism under Simultaneous Positive Gate and Drain Bias Stress in Self-Aligned Top-Gate Amorphous Indium-Zinc-Oxide Thin-Film Transistors

Abstract: Abstract-We

Cited by 5 publications

References 15 publications

Bi-directional threshold voltage shift of amorphous InGaZnO thin film transistors under alternating bias stress

Bi-directional threshold voltage shift of amorphous InGaZnO thin film transistors under alternating bias stress

Analysis of Threshold Voltage Shift for Full VGS/VDS/Oxygen-Content Span under Positive Bias Stress in Bottom-Gate Amorphous InGaZnO Thin-Film Transistors

Reliability-Aware SPICE Compatible Compact Modeling of IGZO Inverters on a Flexible Substrate

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