Two-dimensional a-Si:H based $n-i-p$ sensor array

This article presents the design and fabrication process of a two-dimensional hydrogenated amorphous silicon $(a-Si:H) n-i-p$ photodiode array, developed for low light level sensor applications. Utilization of the single $a-Si:H$ switching diode for signal readout enables simpler device design and fabrication. Since the sensing and switching diodes are formed simultaneously by dry etching the $a-Si:H$ layers deposited over the whole area, the number of masks required in lithography was reduced to six. A significant reduction of the leakage current has been achieved by tailoring defects at the $i-p$ interface and optimizing the plasma processing conditions. Details of device fabrication along with results of the sensor array performance are presented.