Ultrafast self-powered phototransistor based on Te-WSe2 van der Waals heterojunction

Band engineering through the integration of van der Waals heterostructures composed of 2D materials offers a promising approach to achieving high-performance optoelectronic devices. This strategy allows for the fabrication of ultrathin and uniform PN junctions with well-defined band edges, enabling efficient charge transfer and separation. In this study, we have developed a self-powered and highly sensitive photodetector using a van der Waals heterostructure composed of WSe2 and Te. The Te layer was employed as the channel material for the phototransistor, while the out-of-plane Te/WSe2 PN junction served as the charge transfer layer. The vertical built-in electric field present in the PN junction facilitated the separation of photogenerated carriers. The proposed phototransistor demonstrated exceptional self-powered performance characteristics, including a photoresponsivity of 33.08 mA/W, a specific detectivity of 1.57 x 106 Jones, and a fast response time of 2 mu s. These results highlight the effectiveness of the van der Waals heterostructure design in achieving high sensitivity and efficient carrier separation in photodetection applications.