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This paper presents a novel green laser sequential lateral solidification G-SLS process for AMOLED applications. G-SLS utilizes a high frequency pulsed green laser and 2D mask patterns to manipulate the microstructure of crystallize Si films. Mask patterns have been optimized to obtain uniform microstructure of the crystallized Si films at the overlap region. Thin film transistors based on G-SLS processed Si films have mobility of 150.72 cm2/V-sec and a sub-threshold swing of 0.20V/dec. 14″ qFHD AMOLEDs have been fabricated using the G-SLS process. The advantages and issues of G-SLS technology will be further discussed.

For the first time, photo sensors employing p-type Si and IGZO semiconductor (P-I-OS) have been fabricated with a sensor dimension of W/L = 1600/5. The IGZO layer was deposited using DC sputtering and replaces the conventional n+-doped cathode electrode. The P-I-OS photo sensor is more sensitive to light with shorter wavelengths, and high to low photo-current dynamic range is almost constant from −15V to −2.5V of anode bias. The P-I-OS photo sensor exhibits dynamic range of 53.3 dB under −5V of anode bias and 10,000 lx of illuminated light intensity

A new low power consumption amorphous silicon (a-Si:H) TFT level shifter is designed and verified by SPICE simulation. The a-Si:H TFT level shifter employing cascade inverters successfully shifts low voltage (5 V) to high voltage (23 V) by employing a bootstrapping method. Proposed a-Si:H TFT level shifter has considerably reduced the power consumption by 50% compared with the conventional one (8.03 mW) due to connection of clock pulse on the diode connected node and bootstrapping method. The proposed level shifter may be suitable for mobile display applications.

Highly stable voltage programmed a-Si:H TFT pixel circuit for AMOLED, which employs both Vth-compensation and negative bias annealing, is proposed and fabricated. Experimental results, after 60 hours electrical stress at elevated temperature (60°C) show that the OLED current stability in the proposed pixel is considerably improved compared with a conventional 2-TFT pixel, Vth-compensated pixel, and negative bias annealed pixel, respectively. The proposed pixel can reduce the degradation of a-Si:H TFT by employing negative bias annealing store Vth of a-Si:H TFT so that highly stable and uniform a-Si:H TFT backplane for AMOLED. Our proposed pixel may be suitable for highly stable AMOLED employing the a-Si:H TFT.

An excimer-laser-based two-shot sequential lateral solidification (TS-SLS) process has been developed to fabricate 30” FHD (1920×RGB×1080) AMOLED TVs using both 2D projection and line-scan SLS systems. We have optimized (1) the microstructure of TS-SLS processed polycrystalline materials, (2) the geometry of driving TFTs to minimize non-uniformity of the pixel brightness and (3) the off-bias TFT aging process to reduce the leakage current. This result verifies that the TS-SLS process can be utilized to make large area AMOLED TVs without any laser related mura.

We have designed and fabricated a new top gate asymmetric offset structured n-type depletion mode poly-Si TFT of which the leakage current was considerably reduced due to successful suppression of electric field near the drain region caused by the asymmetric offset structure. The TFT was fabricated on the glass substrate by employing alternating magnetic field enhanced rapid thermal annealing (AMFERTA). The a-Si and n+ a-Si layers were deposited successively, and did not use any other ion doping methods. The asymmetric offset structure could be made without additional processes or masks. This new structure suppressed the leakage current to about 86% of non-offset structured AMFERTA poly-Si TFT without considerable sacrifice of on current. This suppression method of leakage current can be helpful to remain the good image quality and save the power consumption of AMOLED panels.

We developed an a-Si TFT-LCD panel with integrated gate driver circuit using a standard 5-MASK process. To minimize the effect of the a-Si TFT current and LC's capacitance variation with temperature, we developed a new a-Si TFT circuit structure and minimized coupling capacitance by changing vertical architecture above gate driver circuit. Integration of gate driver circuit on glass substrate enables single chip and 3-side free panel structure in a-Si TFT-LCD of QVGA(240*320) resolution.