High performance active image sensor pixel design with circular structure oxide TFT

摘要

We report a high-performance active image sensor pixel design by utilizing amorphous-indium-gallium-zinc-oxide(aIGZO) thin-film transistors(TFTs) with a circular structure. The TFT, configured with the inner electrode as source and outer electrode as drain, typically exhibits good saturation electrical characteristics, where the device has a constant drive current despite variations in drain voltage. Due to the very high output resistance exhibited by this asymmetric TFT structure with a circular shape, the pixel circuit considered here in common-drain configuration provides a higher gain of operation than a pixel circuit implemented with rectangular a-IGZO TFTs. They can be used as driving TFTs in active image sensor circuits. They are, therefore,good candidates for digital X-ray detectors in applications such as medical diagnostic procedures.