Photoinduced Orientation‐Dependent Interlayer Carrier Transportation in Cross‐Stacked Black Phosphorus van der Waals Junctions

Abstract A combination of different 2D layered materials by van der Waals (vdW) stacking or lateral splicing provides the basic building blocks for dynamic behavior researches of interlayer carriers. Anisotropic materials, recently, have further attracted attentions in this field because of their supply of freedoms for regulating the performance of electro‐optical devices, whereas detailed characteristics and mechanisms of interlayer carrier transportation in these materials need remain to be revealed. Here, by using the photoassisted field effect and scanning photocurrent imaging measurements, it is demonstrated that the photoinduced interlayer carrier transportation in cross‐stacked black phosphorus (BP) vdW junctions is strongly dependent on the crystal orientation and stacking morphology. Type‐I and II band alignments are respectively predicted in the BP junctions with parallel and vertical crystal orientation stacking. The interlayer carrier transportation with both vertical and lateral modes is observed within only one sample. Combined first principle calculation with band theory analyses, the small band offset for holes and tunneling effect play key roles during the interlayer transportation. These results highlight the importance of crystal orientation of materials in vdW junctions and provide insights, both experimentally and theoretically, into engineering and design of orientation‐based nanodevices.