Joon-hoo Choi

70.1: Invited Paper: Large‐Sized Full Color AMOLED TV: Advancements and Issues

We have demonstrated a 40-inch diagonal, full color WXGA AMOLED TV. It was based on the technologies of amorphous silicon (a-Si) TFT backplane and white OLED with color filter. Despite of recent technology advancement enabling high color purity, large-sized AMOLED, a lot of problems to solve still exist to enter the large-sized display market. Here, Samsung will discuss how far the technologies need to go for the marketplace of large-sized display.

Construction and characterization of an amorphous silicon flat-panel detector based on ion-shower doping process

Abstract In this paper, we introduce a new 36×43 cm 2 amorphous silicon flat-panel detector for digital radiography. A prototype flat-panel detector was fabricated using a p–i–n photodiode/thin-film transistor (TFT) array. The main difference of this flat panel detector to the similar general flat-panel detectors is p–i–n photodiode fabrication method. The p-layer of diode is formed using an ion shower doping method instead of the conventional PECVD method to increase the quality of array. The diode shows a leakage current of 2 pA/mm 2 at −5 V and dark current uniformity of the detector is 2.5%. The modulation transfer function (MTF) of the detector is 0.41 at 2 lp/mm .

49.1: A 14.1 inch Full Color AMOLED Display with Top Emission Structure and a‐Si TFT Backplane

A structure and a design of device were developed to fabricate large-scale active matrix organic light-emitting diode (AMOLED) display with good color purity and high aperture ratio. With these technologies, we developed a full color 14.1 inch WXGA AMOLED display. For the integration of OLED on an active matrix a-Si TFT backplane, an efficient top emission OLED is essential since the TFT circuitry covers a large position of the pixel aperture. These technologies will enable up the OLED applications to larger size displays such as desktop monitors and TVs.

High transmittance TFT-LCD panels using low-/spl kappa/ CVD films

Thin-film transistor liquid crystal display (TFT-LCD) panels of a high transmittance structure were fabricated by using a low-/spl kappa/ dielectric film as a passivation layer. The low-dielectric films were successfully deposited and patterned using a conventional plasma-enhanced chemical vapor deposition (PECVD) and plasma-assisted etching techniques. The interface between the a-Si channel and the overlaying passivation was modified by appropriate plasma treatment prior to the low-/spl kappa/ deposition. TFTs having the a-Si:C:O:H passivation showed a transfer characteristics similar to that of conventional TFTs. The high transmittance panel showed brightness approximately 30% higher than that of a standard panel without degrading other display characteristics, such as crosstalk.

68.2: Achieving High Color Gamut with Microcavity on White OLED

We have demonstrated bottom-emission white OLED devices, which have RGBW sub-pixel and high color gamut over 100% NTSC ratio with White-to-Green microcavity technique. Large-Sized AMOLED TV has to show very high quality display images to overcome LCD TV. However, the R, G and B colors filtered by LCD color-filters are not saturated enough. Especially, green emission peak is very broad because blue emission peak is not removed perfectly by green color-filter. Therefore, we fabricate white OLED having saturated green color by adapting microcavity technique. The results of green pixels are (0.211, 0.723) in color coordinates, and the efficiency of green is 15.4 cd/A, which was (0.217, 0.600) and 7.5 cd/A. And the color gamut with microcavity reaches more than 100% NTSC.

Reliable Characterization of Microcrystalline Silicon Films for Thin Film Transistor Applications

Despite many years of research on microcrystalline silicon films, these materials have not yet found industrial application as thin film transistors. We discuss difficulties in their accurate characterization and compare the advantages and disadvantages of commonly used characterization techniques. Our results show that no single technique provides a complete characterization of these films, and that a combination of techniques is required for a detailed and reliable picture of the film microstructure. Nevertheless, in the case of optimized films, most of the information on the film microstructure can be derived from spectroscopic ellipsometry alone.

New Fraction Time Annealing Method For Improving Organic Light Emitting Diode Current Stability of Hydorgenated Amorphous Silicon Thin-Film Transistor Based Active Matrix Organic Light Emitting Didode Backplane

We propose and fabricate a new hydrogenated amorphous silicon (a-Si:H) thin-film transistor (TFT) pixel employing a fraction time annealing (FTA), which can supply a negative gate bias during a fraction time of each frame rather than the entire whole frame, in order to improve the organic light emitting diode (OLED) current stability for an active matrix (AM) OLED. When an electrical bias for an initial reference current of 2 µA at 60 °C is applied to an FTA-driven pixel more than 100 h and the temperature is increased up to 60 °C rather than room temperature, the OLED current is reduced by 22% in the FTA-driven pixel, whereas it is reduced by 53% in a conventional pixel. The current stability of the proposed pixel is improved, because the applied negative bias can suppress the threshold voltage degradation of the a-Si:H TFT itself, which may be attributed to hole trapping into SiNx. The proposed fraction time annealing method can successfully suppress Vth shift of the a-Si:H TFT itself due to hole trapping into SiNx induced by negative gate bias annealing.

3-dimensional analysis on the cell string current of NAND flash memory

The cell string current of NAND flash memory is very small due to large resistance from the cells connected in series. In this paper, scaling effects on the cell current are analyzed for 70/60/50 nm NAND flash technologies using 3-dimensional TCAD simulation. The geometrical and process parameters are varied and their effects are quantified. It is identified that the coupling ratio has the most significant impact on the cell current and the LDD engineering is more relevant for higher cell current

Leakage current of amorphous silicon p-i-n diodes made by ion shower doping

In this letter, we report the leakage current of amorphous silicon (a-Si:H) p-i-n photodiodes, of which the p layer is formed by ion shower doping. The ion shower doping technique has an advantage over plasma-enhanced chemical vapor deposition (PECVD) in the fabrication of a large-area amorphous silicon flat-panel detector. The leakage current of the ion shower diodes shows a better uniformity within a 30 cm×40 cm substrate than that of the PECVD diodes. However, it shows a higher leakage current of 2–3 pA/mm2 at −5 V. This high current originates from the high injection current at the p-i junction.

16.4: A 14.1″ WXGA Solution Processed OLED Display with a‐Si TFT

We have developed the worlds largest a-Si TFT based solution processed AMOLED full color display. In our 14.1″ WXGA demonstrator, we have realized the worlds best performance for solution-processed OLED materials in an active matrix display, while setting a higher standard for uniformity and image quality.