Atomically thin binary V-V compound semiconductor: a first-principles study

Finding novel 2D semiconductors is crucial to develop next-generation low-dimensional electronic devices. Using first-principles calculations, we propose a class of unexplored binary V-V compound semiconductors (PN, AsN, SbN, AsP, SbP and SbAs) with monolayer black phosphorene (alpha) and blue phosphorene (beta) structures. Our phonon spectra and room-temperature molecular dynamics (MD) calculations indicate that all compounds are very stable. Moreover, most of compounds are found to present a moderate energy gap in the visible frequency range, which can be tuned gradually by in-plane strain. Especially, alpha-phase V-V compounds have a direct gap, while b-SbN, AsN, SbP, and SbAs may be promising candidates for 2D solar cell materials due to a wide gap separating acoustic and optical phonon modes. Furthermore, vertical heterostructures can be also built using lattice matched alpha(beta)-SbN and phosphorene, and both vdW heterostructures are found to have intriguing direct band gaps. The present investigation not only broadens the scope of layered group V semiconductors but also provides an unprecedented route for the potential applications of 2D V-V families in optoelectronic and nanoelectronic semiconductor devices.