scholarly journals Effects of polyimide curing on image sticking behaviors of flexible displays

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hyojung Kim ◽  
Jongwoo Park ◽  
Sora Bak ◽  
Jungmin Park ◽  
Changwoo Byun ◽  
...  
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
Curing Temperature ◽  
Indium Gallium Zinc Oxide ◽  
Threshold Voltage Shift ◽  
Flexible Displays ◽  
Metal Insulator Metal ◽  
Display Technology ◽  
Bias Temperature Stress ◽  
Materials Used ◽  
Charging Effect

AbstractFlexible displays on a polyimide (PI) substrate are widely regarded as a promising next-generation display technology due to their versatility in various applications. Among other bendable materials used as display panel substrates, PI is especially suitable for flexible displays for its high glass transition temperature and low coefficient of thermal expansion. PI cured under various temperatures (260 °C, 360 °C, and 460 °C) was implemented in metal–insulator–metal (MIM) capacitors, amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFT), and actual display panels to analyze device stability and panel product characteristics. Through electrical analysis of the MIM capacitor, it was confirmed that the charging effect in the PI substrates intensified as the PI curing temperature increased. The threshold voltage shift (ΔVth) of the samples was found to increase with rising curing temperature under negative bias temperature stress (NBTS) due to the charging effect. Our analyses also show that increasing ΔVth exacerbates the image sticking phenomenon observed in display panels. These findings ultimately present a direct correlation between the curing temperature of polyimide substrates and the panel image sticking phenomenon, which could provide an insight into the improvement of future PI-substrate-based displays.

scholarly journals Significant Performance and Stability Improvements of Low-Temperature IGZO TFTs by the Formation of In-F Nanoparticles on an SiO2 Buffer Layer

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1165 ◽  
Author(s):  
Ho-young Jeong ◽  
Seung-hee Nam ◽  
Kwon-shik Park ◽  
Soo-young Yoon ◽  
Chanju Park ◽  
...  
Keyword(s):  
Low Temperature ◽  
Buffer Layer ◽  
Atom Probe ◽  
Indium Gallium Zinc Oxide ◽  
Threshold Voltage Shift ◽  
Oxide Electronics ◽  
Information Displays ◽  
Significant Performance ◽  
Atom Probe Tomography Analysis ◽  
Bias Temperature Stress

We report the performance improvement of low-temperature coplanar indium–gallium–zinc–oxide (IGZO) thin-film transistors (TFTs) with a maximum process temperature of 230 °C. We treated F plasma on the surface of an SiO2 buffer layer before depositing the IGZO semiconductor by reactive sputtering. The field-effect mobility increases from 3.8 to 9.0 cm2 V−1·s−1, and the threshold voltage shift (ΔVth) under positive-bias temperature stress decreases from 3.2 to 0.2 V by F-plasma exposure. High-resolution transmission electron microscopy and atom probe tomography analysis reveal that indium fluoride (In-F) nanoparticles are formed at the IGZO/buffer layer interface. This increases the density of the IGZO and improves the TFT performance as well as its bias stability. The results can be applied to the manufacturing of low-temperature coplanar oxide TFTs for oxide electronics, including information displays.

scholarly journals Poly(amide-imide) materials for transparent and flexible displays

2018 ◽  
Vol 4 (10) ◽  
pp. eaau1956 ◽  
Author(s):  
Sun Dal Kim ◽  
Byungyong Lee ◽  
Taejoon Byun ◽  
Im Sik Chung ◽  
Jongmin Park ◽  
...  
Keyword(s):  
Thin Film Transistors ◽  
High Performance ◽  
Coefficient Of Thermal Expansion ◽  
Oxide Thin Film ◽  
Indium Gallium Zinc Oxide ◽  
Zinc Oxide Thin Film ◽  
Flexible Displays ◽  
Aromatic Polyimides ◽  
High Performance Polymer ◽  
Indium Gallium

The key component currently missing for the next generation of transparent and flexible displays is a high-performance polymer material that is flexible, while showing optical and thermal properties of glass. It must be transparent to visible light and show a low coefficient of thermal expansion (CTE). While specialty plastics such as aromatic polyimides are promising, reducing their CTE and improving transparency simultaneously proved challenging, with increasing coloration the main problem to be resolved. We report a new poly(amide-imide) material that is flexible and displays glass-like behavior with a CTE value of 4 parts per million/°C. This novel polymer was successfully used as a substrate to fabricate transparent and flexible indium-gallium-zinc oxide thin-film transistors.

scholarly journals Threshold voltage instability and polyimide charging effects of LTPS TFTs for flexible displays

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hyojung Kim ◽  
Jongwoo Park ◽  
Taeyoung Khim ◽  
Sora Bak ◽  
Jangkun Song ◽  
...  
Keyword(s):  
Glass Substrate ◽  
Stress Test ◽  
Gate Bias ◽  
Metal Insulator ◽  
Flexible Displays ◽  
Voltage Instability ◽  
Metal Insulator Metal ◽  
Tcad Simulation ◽  
Bias Temperature Stress ◽  
P Type

AbstractIn this paper, we investigate the Vth shift of p-type LTPS TFTs fabricated on a polyimide (PI) and glass substrate considering charging phenomena. The Vth of the LTPS TFTs with a PI substrate positively shift after a bias temperature stress test. However, the Vth with a glass substrate rarely changed even with increasing stress. Such a positive Vth shift results from the negative charging of fluorine stemmed from the PI under the gate bias. In fact, the C–V characterization on the metal–insulator-metal capacitor reveals that charging at the SiO2/PI interface depends on the applied gate bias and the PI material, which agrees well with the TCAD simulation and SIMS analyses. As a result, the charging at the SiO2/PI interface contributes to the Vth shift of the LTPS TFTs leading to image sticking.

1700V, 5.5mOhm-cm2 4H-SiC DMOSFET with Stable 225°C Operation

2014 ◽  
Vol 778-780 ◽  
pp. 903-906 ◽  
Author(s):  
Kevin Matocha ◽  
Kiran Chatty ◽  
Sujit Banerjee ◽  
Larry B. Rowland
Keyword(s):  
High Temperature ◽  
Temperature Stress ◽  
High Temperatures ◽  
Threshold Voltage ◽  
Room Temperature ◽  
Gate Bias ◽  
Threshold Voltage Shift ◽  
Device Reliability ◽  
Bias Temperature Stress ◽  
High Temperature Operation

We report a 1700V, 5.5mΩ-cm24H-SiC DMOSFET capable of 225°C operation. The specific on-resistance of the DMOSFET designed for 1200V applications is 8.8mΩ-cm2at 225°C, an increase of only 60% compared to the room temperature value. The low specific on-resistance at high temperatures enables a smaller die size for high temperature operation. Under a negative gate bias temperature stress (BTS) at VGS=-15 V at 225°C for 20 minutes, the devices show a threshold voltage shift of ΔVTH=-0.25 V demonstrating one of the key device reliability requirements for high temperature operation.

Effect of Curing Temperature on Hardened Concrete Properties

2005 ◽  
Vol 1914 (1) ◽  
pp. 97-104 ◽  
Author(s):  
W. Micah Hale ◽  
Thomas D. Bush ◽  
Bruce W. Russell ◽  
Seamus F. Freyne
Keyword(s):  
Fly Ash ◽  
Cementitious Materials ◽  
Curing Temperature ◽  
Supplementary Cementitious Materials ◽  
Cold Weather ◽  
Strength Development ◽  
Hardened Concrete ◽  
Hardened Properties ◽  
Hot Weather ◽  
Materials Used

Often, concrete is not mixed or placed under ideal conditions. Particularly in the winter or the summer months, the temperature of fresh concrete is quite different from that of concrete mixed under laboratory conditions. This paper examines the influence of supplementary cementitious materials on the strength development (and other hardened properties) of concrete subjected to different curing regimens. The supplementary cementitious materials used in the research program were ground granulated blast furnace slag (GGBFS), fly ash, and a combination of both materials. The three curing regimens used were hot weather curing, standard curing, and cold weather curing. Under the conditions tested, the results show that the addition of GGBFS at a relatively low replacement rate can improve the hardened properties for each curing regimen. This improvement was noticeable not only at later ages but also at early ages. Mixtures that contained both materials (GGBFS and fly ash) performed as well as and, in most cases, better than mixtures that contained only portland cement in all curing regimens.

Experiment and Numerical Analysis of the Residual Stresses in Underfill Resins for Flip Chip Package Applications

2005 ◽  
Vol 127 (1) ◽  
pp. 47-51 ◽  
Author(s):  
Man-Lung Sham ◽  
Jang-Kyo Kim
Keyword(s):  
Numerical Analysis ◽  
Residual Stresses ◽  
Integrated Circuit ◽  
Flip Chip ◽  
Coefficient Of Thermal Expansion ◽  
Flexural Modulus ◽  
Curing Temperature ◽  
Electronic Packages ◽  
Element Analysis ◽  
Plastic Package

Polymeric encapsulant is widely used to protect the integrated circuit chips and thus to enhance the reliability of electronic packages. Residual stresses are introduced in the plastic package when the polymer is cooled from the curing temperature to ambient, from which many reliability issues arise, including warpage of the package, premature interfacial failure, and degraded interconnections. Bimaterial strip bending experiment has been employed successfully to monitor the evolution of the residual stresses in underfrill resins for flip chip applications. A numerical analysis is developed to predict the residual stresses, which agree well with the experimental measurements. The changes of material properties, such as flexural modulus and coefficient of thermal expansion, of the resins with temperature are taken into account in the finite element analysis.

Chitin Nanofibers / Epoxy Resin Optically Transparent Nanocomposite Films

2012 ◽  
Vol 602-604 ◽  
pp. 1479-1483 ◽  
Author(s):  
Xu Shao ◽  
Da Gang Li ◽  
Ai Jun Li ◽  
Wen Biao Gu
Keyword(s):  
Epoxy Resin ◽  
Coefficient Of Thermal Expansion ◽  
Optoelectronic Devices ◽  
Nanocomposite Films ◽  
Light Transmittance ◽  
The Novel ◽  
Flexible Displays ◽  
Novel Material ◽  
Ph Conditions ◽  
Chitin Nanofibers

Chitin nanofibers were prepared from prawn shell by a simple mechanical treatment after the removal of proteins and minerals. Since the exoskeleton of prawn is made up of a finer structure nano-fibrillation of prawn shell is easy, which allows chitin nanofibers to be prepared under neutral pH conditions. The obtained nanofibers were observed by FE-SEM and found to have a uniform width of approximately 20-40nm and high aspect ratio that more than 1000. Due to the size effect of the chitin nanofibers, the nanocomposite films had high transparency that the chitin nanofibers/epoxy resin nanocomposite transmitted 85.2% of light compared to the light transmittance of pure epoxy resin（91%）and the light transmittance of pure chitin nanofibers sheet (70.1%) at a visible wavelength of 600nm. In the study the coefficient of thermal expansion (CTE) from 20 to 160°C of the epoxy resin sheet was measured to be 170 ppm/K. By adding 40 wt% of chitin nanofibers, the CTE of the epoxy resin dropped to 22 ppm/K, approximately 1/8th of its original value. The novel material is a candidate for transparent substrates in the manufacturing optoelectronic devices such as flexible displays and solar cells.

scholarly journals Remarkable Stability Improvement of ZnO TFT with Al2O3 Gate Insulator by Yttrium Passivation with Spray Pyrolysis

Nanomaterials ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 976 ◽  
Author(s):  
Jewel Kumer Saha ◽  
Ravindra Naik Bukke ◽  
Narendra Naik Mude ◽  
Jin Jang
Keyword(s):  
Spray Pyrolysis ◽  
Threshold Voltage ◽  
Moisture Absorption ◽  
Thin Film Transistor ◽  
Gate Insulator ◽  
Zno Films ◽  
Threshold Voltage Shift ◽  
Bias Temperature Stress ◽  
The Stability ◽  
The Impact

We report the impact of yttrium oxide (YOx) passivation on the zinc oxide (ZnO) thin film transistor (TFT) based on Al2O3 gate insulator (GI). The YOx and ZnO films are both deposited by spray pyrolysis at 400 and 350 °C, respectively. The YOx passivated ZnO TFT exhibits high device performance of field effect mobility (μFE) of 35.36 cm2/Vs, threshold voltage (VTH) of 0.49 V and subthreshold swing (SS) of 128.4 mV/dec. The ZnO TFT also exhibits excellent device stabilities, such as negligible threshold voltage shift (∆VTH) of 0.15 V under positive bias temperature stress and zero hysteresis voltage (VH) of ~0 V. YOx protects the channel layer from moisture absorption. On the other hand, the unpassivated ZnO TFT with Al2O3 GI showed inferior bias stability with a high SS when compared to the passivated one. It is found by XPS that Y diffuses into the GI interface, which can reduce the interfacial defects and eliminate the hysteresis of the transfer curve. The improvement of the stability is mainly due to the diffusion of Y into ZnO as well as the ZnO/Al2O3 interface.

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