High-sensitive two-dimensional PbI 2 photodetector with ultrashort channel

Photodetectors based on two-dimensional (2D) semiconductors have attracted many research interests owing to their excellent optoelectronic characteristics and application potential for highly integrated applications. However, the unique morphology of 2D materials also restricts the further improvement of the device performance, as the carrier transport is very susceptible to intrinsic and extrinsic environment of the materials. Here, we report the highest responsivity (172 A/W) achieved so far for a PbI 2-based photodetector at room temperature, which is an order of magnitude higher than previously reported. Thermal scanning probe lithography (t-SPL) was used to pattern electrodes to realize the ultrashort channel (~60 nm) in the devices. The shortening of the channel length greatly reduces the probability of the photo-generated carriers being scattered during the transport process, which increases the photocurrent density and thus the responsivity. Our work shows that the combination of emerging processing technologies and 2D materials is an effective route to shrink device size and improve device performance.