Intermixing‐Driven Growth of Highly Oriented Indium Phosphide on Black Phosphorus

Abstract Interface control plays a critical role in governing various physical and electronic phenomena, as it significantly influences material properties and device performance. In particular, the interfacial structures and properties of 2D layered crystals in contact with metal or dielectrics have recently attracted considerable attention for nanoelectronic applications owing to their superior scalability and functionality. Nonetheless, a comprehensive understanding of the diverse interfacial phenomena in 2D crystals remains limited, especially for chemically reactive 2D semiconducting systems. Here, the controlled intermixing and compound formation at the metal/elemental 2D semiconductor interface are investigated. Black phosphorus (BP) exhibits intermixing with In, leading to the formation of highly oriented interfacial InP. Comprehensive structural characterizations, including electron diffraction, atomic‐resolution scanning transmission electron microscopy, X‐ray photoelectron spectroscopy, and Raman spectroscopy, confirm the InP interfacial structure. Furthermore, electrical tunability of the BP channel is demonstrated by varying both the initial BP thickness and the amount of In deposited, revealing two competing effects: 1) thinning‐induced bandgap widening of BP, and 2) charge‐transfer‐induced effective bandgap narrowing. The resulting tunable transport characteristics highlight the significance of interfacial compound formation in BP, providing fundamental insights into the tunable properties of diverse 2D heterointerfaces for multifunctional device architectures.