Epitaxial growth of black phosphorene enabled on black-phosphorene-like group IV-VI substrates

Black phosphorene (BlackP) is a promising two-dimensional material for next-generation nanoelectronics with a thickness-dependent bandgap and high carrier mobility. Yet to date, epitaxial growth of BlackP on a proper substrate remains a daunting challenge, which in turn prevents its mass production for device applications. Here we propose that BlackP-like group IV-VI substrates can be ideal candidates to promote epitaxial growth of BlackP. We first show, using first-principles approaches, that BlackP is energetically and thermodynamically stable on SnSe(001) as a representative substrate, which can be attributed to the isovalency nature and inherent structural similarity between the two. In contrast, as a close isomer of BlackP, blue phosphorene is thermodynamically unstable on SnSe(001). Next, we show that two phosphorus adatoms not only can readily form a dimer via P-P attraction, but such dimers also can diffuse isotropically and much faster than P monomers, both aspects highly desirable for initial growth and mass production of BlackP. Furthermore, BlackP grown on such semiconducting substrates can be directly exploited as a platform for novel optoelectronic devices, as demonstrated using the BlackP/SnSe heterobilayer that possesses a type-II band alignment and favors the formation of indirect excitons with desirable functionalities.