Precise p‐Type Substitutional Doping Enables WS ₂ p‐n Anti‐Ambipolar Homojunction Phototransistor Arrays

Abstract Van der Waals (vdWs) p–n junctions assembled from 2D materials offer enhanced flexibility for creating versatile electronic and optoelectronic devices, attracting significant interest. However, the lack of reliable methods to produce high‐quality p‐type 2D semiconductors, especially patterned p‐type channels, remains a major challenge for progress in the field. Here, a precise substitutional doping strategy for 2D semiconductors is presented, enabling the production of millimeter‐scale WS ₂ single‐crystal thin films with tailored p‐type and n‐type properties. This advancement supports the fabrication of high‐performance WS ₂ ‐based p‐type and n‐type field‐effect transistor (FET) miniaturized arrays with near‐ohmic contact. Building on this progress, a WS ₂ van der Waals homojunction p‐n array demonstrating distinct anti‐ambipolar behavior and excellent rectification characteristics is developed. In self‐powered photodetection mode, leveraging the strong coupling of the vdWs homojunction interface, the device achieves an exceptional photovoltaic effect with a high specific detectivity of 3.4 × 10 ¹⁰ Jones and a fast response time of 400 µs. The development of WS ₂ p‐n homojunction arrays presents immense potential for advancing next‐generation logic electronics and optoelectronic devices, opening new avenues for large‐scale industrial applications.