High-Frequency Half-Bit Shift Register With Amorphous-Oxide TFT

We have designed, fabricated, and successfully characterized a ten-stage half-bit shift register utilizing amorphous In-Ga-Zn-O (a-IGZO) thin-film-transistor (TFT) technology. High-performance bottom-gate staggered TFT structures with aluminum source, drain, and gate electrodes and RF-sputtered a-IGZO active material has been developed with a field-effect mobility of 16 cm2/V ·s. The half-bit shift register, which consists of only seven transistors per stage, has been successfully driven at a maximum clock frequency of 40 kHz (sufficient to drive a full VGA display at a frame rate of more than 80 kHz) and minimum rail-to-rail supply voltage of 20 V. This effort further demonstrates the potential of oxide-TFT technology to be employed for systems with higher integration level.