Monolayer diboron dinitride: Direct band-gap semiconductor with high absorption in the visible range

Ershad Rad, Soheil/0000-0001-8947-9625WOS: 000518534400009We predict a two-dimensional monolayer polymorph of boron nitride in an orthorhombic structure (o-B2N2) using first-principles calculations. Structural optimization, phonon dispersion, and molecular dynamics calculations show that o-B2N2 is thermally and dynamically stable. o-B2N2 is a semiconductor with a direct band gap of 1.70 eV according to calculations based on hybrid functionals. The structure has high optical absorption in the visible range in the armchair direction while low absorption in the zigzag direction. This anisotropy is also present in electronic and mechanical properties. The in-plane stiffness of o-B2N2 is very close to that of hexagonal boron nitride. The diatomic building blocks of this structure hint at its possible synthesis from precursors having B-B and N-N bonds.Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [118F097]; Turkish Academy of Sciences-Outstanding Young Scientists Award Program (TUBA-GEBIP)Turkish Academy of Sciences; National Center for High Performance Computing of Turkey (UHeM)Istanbul Technical University [5003622015]This work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) under Project No. 118F097. S.J. acknowledges support from the Turkish Academy of Sciences-Outstanding Young Scientists Award Program (TUBA-GEBIP). Part of the computational resources is provided by the National Center for High Performance Computing of Turkey (UHeM) under Grant No. 5003622015. S.D. thanks UNAM, National Nanotechnology Research Center at Bilkent University for the hospitality