Effect of bias stress on mechanically strained low temperature polycrystalline silicon thin film transistor on stainless steel substrate

Peng, I-Hsuan; Liu, Po–Tsun; Wu, Tai–Bor

doi:10.1063/1.3193654

Cited by 26 publications

(10 citation statements)

References 13 publications

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“…tensile strain is applied to the device, with degradation at R = 30 mm smaller than R = 20 mm. These results were similar to those in previous reports, indicating that the average distance between Si-Si bonds is distorted in the poly-Si film [7], and hole mobility decreases, originating from the split between the light hole and heavy hole energy bands and an increase in mean free time on the surface orientation of poly-Si when the uniaxial tensile strain is parallel to the channel direction [4], [8].…”

Section: Methodssupporting

confidence: 92%

NBTI Degradation in LTPS TFTs Under Mechanical Tensile Strain

Lin

Chen

Chang

et al. 2011

IEEE Electron Device Lett.

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This letter investigates the negative-bias temperature instability (NBTI) degradation of p-channel low-temperature polycrystalline-silicon thin-film transistors (LTPS TFTs) under mechanical tensile stress. Experimental results reveal that the interface state density N it and grain boundary trap density N trap of tensile-strained LTPS TFTs are more pronounced than those of unstrained LTPS TFTs. Extracted density of states and conduction activation energy E a both show increases due to the strained Si-Si bonds, which implies that strained Si-Si bonds are able to react with dissociated H during NBTI stress. Therefore, NBTI degradation is more significant after tensile strain than in an unstrained condition.

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Section: Methodssupporting

confidence: 92%

NBTI Degradation in LTPS TFTs Under Mechanical Tensile Strain

Lin

Chen

Chang

et al. 2011

IEEE Electron Device Lett.

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“…Further, the current differences increased with the gate voltage (V G ). The strain on the substrate surface (ε surface ) at a certain bending curvature radius (R) can be expressed using the equation [16] [17], and the Y s of SS substrates is ∼200 GPa [18]. Hence, χ should be quite small as well.…”

Section: Resultsmentioning

confidence: 99%

Influence of mechanical strain on the electrical properties of flexible organic thin-film transistors

Chen¹,

Chen

Zeng

et al. 2011

Semicond. Sci. Technol.

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In this study, we systematically investigated the bending effect on the electrical properties of flexible organic thin-film transistors (OTFTs) fabricated on stainless steel substrates. We found that the compressive strain resulted in an increased mobility, while the tensile strain degraded the electrical performance. We further used a transfer line method to extract the channel and parasitic resistances under either compressive or tensile strain. The results indicated that the parasitic resistance increased apparently under the tensile bending condition, which probably could be attributed to the damage of the source/drain contacts. Additionally, we deduced that mechanical strains influence the energy barrier height between the grains of pentacene thin films, thereby resulting in the variation of channel resistances. Overall, the flexible OTFTs fabricated on the metal foils exhibited high mechanical flexibility and stability.

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“…Currently, however, few studies have demonstrated the resilience necessary to achieve foldable devices, and further gains in strength must be realized for broad flexible applications. Electrical characteristics under strain in LTPS TFTs on a flexible substrate have been previously reported. − However, the specific degraded region in TFTs and its degradation mechanisms have not yet been adequately studied.…”

Section: Introductionmentioning

confidence: 99%

Surface Engineering of Polycrystalline Silicon for Long-Term Mechanical Stress Endurance Enhancement in Flexible Low-Temperature Poly-Si Thin-Film Transistors

Chen¹,

Chang

Chang³

et al. 2017

ACS Appl. Mater. Interfaces

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The surface morphology in polycrystalline silicon (poly-Si) film is an issue regardless of whether conventional excimer laser annealing (ELA) or the newer metal-induced lateral crystallization (MILC) process is used. This paper investigates the stress distribution while undergoing long-term mechanical stress and the influence of stress on electrical characteristics. Our simulated results show that the nonuniform stress in the gate insulator is more pronounced near the polysilicon/gate insulator edge and at the two sides of the polysilicon protrusion. This stress results in defects in the gate insulator and leads to a nonuniform degradation phenomenon, which affects both the performance and the reliability in thin-film transistors (TFTs). The degree of degradation is similar regardless of bending axis (channel-length axis, channel-width axis) or bending type (compression, tension), which means that the degradation is dominated by the protrusion effects. Furthermore, by utilizing long-term electrical bias stresses after undergoing long-tern bending stress, it is apparent that the carrier injection is severe in the subchannel region, which confirms that the influence of protrusions is crucial. To eliminate the influence of surface morphology in poly-Si, three kinds of laser energy density were used during crystallization to control the protrusion height. The device with the lowest protrusions demonstrates the smallest degradation after undergoing long-term bending.

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Effect of bias stress on mechanically strained low temperature polycrystalline silicon thin film transistor on stainless steel substrate

Cited by 26 publications

References 13 publications

NBTI Degradation in LTPS TFTs Under Mechanical Tensile Strain

NBTI Degradation in LTPS TFTs Under Mechanical Tensile Strain

Influence of mechanical strain on the electrical properties of flexible organic thin-film transistors

Surface Engineering of Polycrystalline Silicon for Long-Term Mechanical Stress Endurance Enhancement in Flexible Low-Temperature Poly-Si Thin-Film Transistors

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