Development of a high resolution, active matrix, flat-panel imager with enhanced fill factor

The development and initial characterization of an active matrix, flat-panel imager (AMFPI) incorporating a newly designed, indirect-detection array is reported. The array has a 127 mu m pitch, a 153x1920 pixel format, and incorporates a pixel design comprising a discrete a-Si:H photodiode coupled to an a-Si:H thin-film transistor (TFT). The array represents an aggressive redesign of a previously reported array having the same pitch and format. In particular, this new array was designed with the dual goals of maximizing the optical fill factor so as to enhance sensitivity as well as minimizing the data line capacitance so as to reduce additive electronic noise. Although constrained by the use of discrete (as opposed to continuous) photodiodes, the new design nevertheless successfully achieves a fill factor of similar to 56% along with a data line capacitance of similar to 50 pF which are significant improvements over the previous design. In this paper, considerations in the design of such arrays are reviewed and performance results of the AMFPI, based on initial empirical results and theoretical considerations, are presented. Finally, possible trends in the future development of indirect and direct detection AMFPIs are described.