Effects of Repetitive Mechanical Bending Strain on Various Dimensions of Foldable Low Temperature Polysilicon TFTs Fabricated on Polyimide

Chen, Bo-Wei; Chang, Ting‐Chang; Hung, Yu-Ju; Huang, Sheng-Lung; Liao, Po‐Yung; Yang, Chung‐Yi; Chu, Ann-Kuo; Wang, Terry Tai-Jui; Chang, Tsu‐Chiang; Su, Bo-Yuan; Kuo, Su-Chun; Huang, I‐Yu

doi:10.1109/led.2016.2584138

Cited by 44 publications

(17 citation statements)

References 23 publications

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“…The increased response time after 5000 bending is attributed to the threshold voltage shift due to increased electron traps in SiO 2 . [ 35 ] Although the response time was increased after 5000 bending cycles, the sensor was still able to detect H 2 with different concentrations. The sensor responses under static bending were also presented in Figure S6, Supporting Information.…”

Section: Resultsmentioning

confidence: 99%

Fast Flexible Bottom‐Gated Hydrogen Sensor Based on Silicon Nanomembrane

Cho

Kim

et al. 2021

Adv Materials Technologies

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High performance flexible hydrogen sensor using a silicon nanomembrane (Si NM) coated with palladium nanoparticles (Pd NPs) is developed. After the formation of gate structure on a released Si NM, selectively pre‐doped Si NM is flip‐transferred onto a plastic substrate. Along with Pd NPs deposited on top of the Si channel, the bottom gate structure allows the sensor to operate in a sub‐threshold regime maximizing the response and recovery speed. A device simulation study revealed that the current change caused by shifting the threshold voltage upon H2 exposure is the main operating mechanism of the sensor. The fabricated sensor shows high response (up to 250% @ 0.7% H2 concentration), short response time (τ10–90 = 10 s), and short recovery time (τ90–10 = 10 s). In addition, the sensor shows low detection limit (50 ppm) and high mechanical robustness.

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Section: Resultsmentioning

confidence: 99%

Fast Flexible Bottom‐Gated Hydrogen Sensor Based on Silicon Nanomembrane

Cho

Kim

et al. 2021

Adv Materials Technologies

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“…Chen et al reported that positive gate sweep after mechanical stress on poly‐Si TFT causes the electron trapping at GBs. [ 29,30 ] Therefore, the V TH shifts to positive after out‐folding stress. If the atomic bonds in poly‐Si and SiO 2 are broken or weakened, O, H, and hydroxyl (OH) could be formed inside the GI and GI/poly‐Si interface.…”

Section: Resultsmentioning

confidence: 99%

“…The electrical stability of the LTPS TFT can be affected by the mechanical strain. [ 26–34 ] Contrastingly, electro‐thermal (positive bias temperature stress (PBTS) or negative bias temperature stress (NBTS) after mechanical strain [ 35 ] can also severely deteriorate the electrical characteristics, which needs to be further studied.…”

Section: Introductionmentioning

confidence: 99%

Excellent Mechanical Durability of In‐Folding Stress of Poly‐Si Thin‐Film Transistor on Plastic Substrate Compared with Out‐Folding: Generation of Gate Leakage Currents in Flexible Poly‐Si Thin‐Film Transistor by Out‐Folding and Bias‐Temperature Stress

et al. 2020

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The effect of electro‐thermal stress on the electrical performance of flexible, low‐temperature polysilicon (LTPS) thin‐film transistors (TFTs) after mechanical‐folding stress aiming to improve the reliability of foldable display backplanes is studied (IG). Herein, for the first time, the significant increase of gate leakage currents upon the negative bias temperature stress (NBTS) or positive bias temperature stress (PBTS) after the out‐folding test on excimer laser annealing (ELA) TFTs is reported. Out‐folding stress increases the drain current, shifts the threshold voltage (ΔVTH) by 2.4 V, and increases the subthreshold swing without affecting the (IG). However, the ΔVTH is 1.8 V upon NBTS, and the negative ΔVTH is −4.7 V upon PBTS after out‐folding stress along with a drastic increase in IG. A thermal annealing at 250 °C for 10 h for the electro‐thermal stressed TFTs after out‐folding is performed, and initial electrical characteristics recovery is achieved; except the abruptly increased IG. These results are correlated with charge trapping at the damaged grain boundary and (GI). A model with moisture/water molecule diffusion through the nanocracks generated by out‐folding is proposed. The ionized charges (H+, OH−) captured at the nanocrack‐induced trap sites in poly‐Si and GI appear to be the origin of abnormal ΔVTH and IG.

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“…[1~3] Also, the subthreshold slope (SS) increases through the generation of interface states and/or the barrier height lowering between source and channel by electron injection into GI, which is proposed to be severe at the poly-Si/SiO2 edge. [1,2,4,5] Field effect mobility also change. The mechanical stress induces an generation of grain boundary trap states, resulting in the decrease of mobilty.…”

Section: Introductionmentioning

confidence: 99%

5‐2: Enhanced Bending Endurance with Transverse Tensile Strain and 4‐Terminal Double Gate LTPS TFTs for flexible AMOLED

Lee

Kang

et al. 2021

Symp Digest of Tech Papers

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This letter investigates the degradation behavior of p‐channel LTPS TFTs on PI substrate under the static bending stress. During 1hr bend, the threshold voltage shifts positively and the subthreshold slope increases slightly. In transverse compressive strain, the field effect mobility increases abruptly with the decrease of the effective channel length and the off state leakage current. This is attributed to the generation of the strain‐induced GI defects near the source and drain terminals, resulting in the trapping of electrons and a shrinkage of the effective channel length and the H passivation of the strained Si bonds in the channel. By inserting the bottom metal layer to block the H diffusion from PI substrate, the controllable normal NBTI behavior is observed in a strained LTPS TFT on PI. These transverse tensile strained and 4‐termianl double gate LTPS TFTs on PI shows as a stable switching TFTs on PI for the flexible system‐on‐panel display.

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Effects of Repetitive Mechanical Bending Strain on Various Dimensions of Foldable Low Temperature Polysilicon TFTs Fabricated on Polyimide

Cited by 44 publications

References 23 publications

Fast Flexible Bottom‐Gated Hydrogen Sensor Based on Silicon Nanomembrane

Fast Flexible Bottom‐Gated Hydrogen Sensor Based on Silicon Nanomembrane

Excellent Mechanical Durability of In‐Folding Stress of Poly‐Si Thin‐Film Transistor on Plastic Substrate Compared with Out‐Folding: Generation of Gate Leakage Currents in Flexible Poly‐Si Thin‐Film Transistor by Out‐Folding and Bias‐Temperature Stress

5‐2: Enhanced Bending Endurance with Transverse Tensile Strain and 4‐Terminal Double Gate LTPS TFTs for flexible AMOLED

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