Low Dark Current Amorphous Silicon Metal-Semiconductor-Metal Photodetector for Digital Imaging Applications

A novel lateral amorphous silicon (a-Si) metal-semiconductor-metal photodetector architecture is proposed using an organic blocking layer. Fabricated devices exhibit low dark-current, high dynamic range, and a measured external quantum efficiency of 65%, which represents a considerable improvement over previously reported designs. The higher performance is enabled by the introduction of a thin organic blocking layer and subsequently operating at high electric-fields. Unlike industry standard p-i-n photodiodes, our high performance lateral photosensor does not require doped p(+)/n(+) layers. Thus, the reported device is compatible with current and previous generation a-Si thin film transistor display fabrication process making it promising for low-cost optical touch panel or diagnostic medical imaging applications.