Low Dark-Current Lateral Amorphous-Selenium Metal-Semiconductor-Metal Photodetector

We report a lateral amorphous-selenium (a-Se) metal-semiconductor-metal detector with a blocking contact. The blocking contact, a polyimide layer, is shown to significantly reduce the dark current even at high applied biases that result in high photo-current-to-dark-current ratios, thus leading to wide dynamic range and high signal-to-noise ratio. The use of the polyimide blocking contact prevents the injection of both holes and electrons and improves considerably upon the high dark current of previously reported lateral a-Se detectors. The proposed detector demonstrates the feasibility of low-cost lateral a-Se devices for indirect conversion digital X-ray imaging applications such as chest radiography, fluoroscopy, and computed tomography.