Conventional light-emitting diodes (LEDs) always pursue the high brightness required for solid-state lighting. However, they always exhibit very low frequency bandwidth of tens MHz. In this letter, we investigate the fabrication and characterization of high-speed GaN-based blue LEDs. The frequency response of LEDs is mainly limited by its diffusion capacitance and resistance, and the injected carriers in the active region of the device. Through appropriate device design, galliumdoped Zinc oxide film deposited by atomic layer deposition is used as the top contact layer with high lateral resistance to self-confine the current injection. In addition, a smaller bonding pad is used to reduce the RC time constant. Thus, the GaN-based blue LEDs with a 75-µm diameter exhibit a 3-dB modulation bandwidth of 225.4 MHz and a light output power of 1.6 mW at the current of 35 mA. Such LEDs can be applied to visible light communication in future.

A new gate driver has been designed and fabricated by amorphous silicon (a-Si) technology. With utilizing four clock signals in the design of gate driver on array (GOA), the pull-up transistor has ability for both output charging and discharging, and layout size of the proposed gate driver can be narrowed for bezel panel application. Moreover, lower duty cycle of clock signals can decrease static power loss to further reduce the overall power consumption of the proposed gate driver. The scan direction of the proposed gate driver can be adjusted by switching two direct control signals to present the reversal display of image. The proposed gate driver has been successfully demonstrated in a 4.5-inch WVGA 480 800 TFT-LCD panel and passed reliability tests of the supporting foundry.Index Terms-Amorphous silicon (a-Si), gate driver, thin-film transistor liquid crystal display (TFT-LCD).

No abstract

No abstract