Ho Kyoon Chung

3.1: Distinguished Paper: 12.1-Inch WXGA AMOLED Display Driven by Indium-Gallium-Zinc Oxide TFTs Array

The full color 12.1-inch WXGA active-matrix organic light emitting diode (AMOLED) display was, for the first time, demonstrated using indium-gallium-zinc oxide (IGZO) thin-film transistors (TFTs) as an active-matrix back plane. It was found that the fabricated AMOLED display did not suffer from the well-known pixel non-uniformity of luminance, even though the simple structure consisting of 2 transistors and 1 capacitor was adopted as a unit pixel circuit, which was attributed to the amorphous nature of IGZO semiconductor. The n-channel a-IGZO TFTs exhibited the field-effect mobility of 8.2 cm2/Vs, threshold voltage of 1.1 V, on/off ratio of > 108, and subthreshold gate swing of 0.58 V/decade. The AMOLED display with a-IGZO TFT array would be promising for large size applications such as note PC and HDTV because a-IGZO semiconductor can be deposited on large glass substrate (> Gen. 7) using conventional sputtering system.

Active-matrix OLED on bendable metal foil

This brief reports a flexible active-matrix organic light-emitting diode display based on a poly-Si thin-film transistor (TFT) backplane. The p-channel poly-Si TFTs on metal foil exhibited a maximum field-effect mobility of 86.1 cm/sup 2//Vs, threshold voltage of 3.5 V, gate voltage swing of 0.8 V/dec, and the minimum off current of 10/sup -12/ A//spl mu/m at V/sub ds/=-0.1 V. A 4.1-in active-matrix backplane was fabricated with the poly-Si TFT with a conventional pixel circuit consisting of 2 TFTs and one capacitor. The scan driver circuits with PMOS were integrated on the flexible metal foil. The top emission, organic light emitting display having a brightness of 100 cd/m/sup 2/.

53.1: Invited Paper: LITI (Laser Induced Thermal Imaging) Technology for High-Resolution and Large-Sized AMOLED

In this paper, we describe a novel color patterning method for the fabrication of high resolution and large format full-color AMOLEDs. Laser Induced Thermal Imaging (LITI) is a laser addressed thermal patterning technology with unique advantages such as excellent transfer film thickness uniformity, multi-layer stack transfer ability, high resolution and scalability to large-Size mother glass. We developed and optimized transfer films, structure of OLED layers, and scanning conditions for the patterning of the evaporated small molecules. As a result, we achieved excellent LITI device stability, which gave the device life time is more than 20,000 hrs with 2.0″ QVGA device architecture for 150 cd/m2 white brightness. As a first step toward the mass production, we set up Gen 4 LITI pilot system.

11.3: Control of Emission Zone in a Full Color AMOLED with a Blue Common Layer

We report a novel structure for a full-color AMOLED (Active Matrix Organic Light Emitting Diode) eliminating the patterning process of a blue emitting layer. The patterning of the three primary colors, RGB, is a key technology in the OLED fabrication process. Conventional full color AMOLED containing RGB layers includes the three opportunities of the defects to make an accurate position and fine resolution using various technologies such as fine metal mask, ink-jet printing and laser-induced transfer system. We can skip the blue patterning step by simply stacking the blue layer as a common layer to the whole active area after pixelizing two primary colors, RG, in the conventional small molecular OLED structure. The red and green pixel showed equivalent performances without any contribution of the blue emission.

53.2: Invited Paper: Large‐Area Color‐Patterning Technology for AMOLED

In this paper, we describe a novel color patterning method for the fabrication of large area full-color AMOLEDs. Laser Induced Thermal Imaging (LITI) is a laser addressed thermal patterning technology with unique advantages such as excellent uniformity of transfer film thickness, capability of multilayer stack transfer, high resolution and scalability to large-Size mother glass. We developed and optimized transfer films, structure of OLED layers, and laser scanning conditions for the patterning of evaporated small molecules. As a result, we achieved excellent LITI device stability which yielded the device life time more than 25,000 hrs at 250 cd/m2 white brightness.

48.3: A 2 Inch LTPS AMOLED with an Embedded Lateral p-i-n Photodiode Sensors

We developed a 2 inch low temperature poly-Si active-matrix organic light-emitting diode (AMOLED) with an embedded p-i-n photodiode. The pixels for both OLED and photodiode are designed using poly-Si TFT and poly-Si p-i-n. The lateral p-i-n photodiode exhibited the photo response of ∼40 dB under 100 lux. We have demonstrated the display and sensors successfully on glass. This technology can be used for AMOLED integrated with touch sensor and brightness control sensor.

Segregation of aluminum in Si and SiO2 films deposited by plasma-enhanced chemical vapor deposition in fabrication of low-temperature poly Si thin-film transitor

Metal contamination in Si and SiO 2 films deposited by plasma-enhanced chemical vapor deposition (PECVD) in the fabrication of low-temperature poly Si thin-film transitor was investigated. Aluminum was the major metal impurity to have the highest concentration. Segregation of Al was always observed in the films deposited at temperatures above 400 °C. The impurity level in the segregated region was 10 1 8 ∼ 10 2 0 atoms/cm 3 for Al, while the concentration in matrix was about 10 1 6 atoms/cm 3 . From the transmission electron microscopy image, the Al segregated region contains small-size Al precipitates. Although the Al impurity level of 10 1 6 atoms/cm 3 did not cause any serious degradation of device performance, the level of 10 1 8 atom/cm3 and higher can induce a fatal degradation of the threshold voltage. This study revealed that the Al originated from the PECVD chamber, carbon precipitates provided the preferred sites for Al precipitates, and the solubility and diffusivity of Al in Si accelerated the segregation of Al.

High-Performance Organic Light-Emitting Diode Displays

The development of new display devices for the interactive communication between computers and people has accelerated over the past decade and considerable progress has recently been made in the area of organic displays. Organic light-emitting devices (OLEDs) are the most suitable candidate to satisfy the demands of next generation displays among the technological options available so far, owing to simple device configuration, high power efficiency and efficient driving schemes, together with solid state encapsulation and excellent user experience. Efficient OLED structures, processes for OLED fabrication, various driving schemes for OLED displays, the current status of fluorescent and phosphorescent OLEDs, top emitting active matrix OLED (AMOLED), passive matrix driving schemes, white OLEDs for high resolution display applications, and thin film transistor (TFT) backplane technology for active matrix OLEDs are discussed here. Finally, the future scope and directions of the high-performance OLED display in mobile display technology and large area TVs are presented.

28.3: Dense Disparity Map Calculation from Color Stereo Images using Edge Information

We have developed the stereo-corresponding algorithm using edge information. The conventional stereo-corresponding algorithm, SAD (Sum of Absolute Difference), has a good quality in case of texture region, but it has a false matching in the non-texture region. In order to reduce the false matching in the non-texture region, the new cost function, which is defined as SED (Sum of Edge Difference) based on the global optimization, is added to the cost function of SAD. We evaluate our algorithm and benchmark Middlebury database. The experimental results show that our proposed algorithm successfully produces piecewise smooth disparity maps while reducing the false matching in the non-texture region. Moreover, our algorithm is faster in getting the best quality than SAD.

Current development status and issues of AMOLED toward an invaluable display

Organic Light-Emitting Device (OLED) has been attracted much interests to realize a flat panel display owing to its promising characteristics. Active matrix OLED can make it possible to make big displays with the good image qualities and create new values and concepts, such as a flexible display, transparent display, and so on. However, in spite of the big potential of the AMOLED, it is still needed to improve lifetime, efficiency and productivity for large size displays. In this paper, we present current development status and issues of the AMOLED toward an ultimate champion among flat panel displays.