Self-Assembly of the Lateral InSe/CuInSe Heterojunction for Enhanced Photodetection.

Layered materials have been found to be promising candidates for next-generation microelectronic and optoelectronic devices due to their unique electrical and optical properties. The p-n junction is an elementary building block for microelectronics and optoelectronics devices. Herein, using the pulsed-laser deposition (PLD) method, we achieve pure InSe-based photodetectors and InSe/CuInSe-based photodetectors with a lateral p-n heterojunction. In comparison to that of the pure InSe-based photodetector, the photodetectors based on the InSe/CuInSe heterojunction exhibit a tremendous promotion of photodetection performance and obvious rectifying behavior. The photoresponsivity and external quantum efficiency of the fabricated heterojunction-based device under 532 nm light irradiation are 20.1 A/W and 4698%, respectively. These values are about 7.5 times higher than those of our fabricated pure InSe-based devices. We attribute this promotion of photodetection to the suitable band structures of InSe and CuInSe, which greatly promote the separation of photoexcited electron-hole pairs. This work suggests an effective way to form lateral p-n junctions, opening up a new scenario for designing and constructing high-performance optoelectronic devices.