First-principles investigation of electronic and mechanical properties of AlN monolayer under hydrogen adsorption

Abstract

We investigate the electronic and mechanical properties of pristine and fully hydrogenated AlN monolayer by first principles calculations. Two different states of hydrogen adsorption on AlN monolayer are considered: (I) adsorption of hydrogen atoms on Aluminum and Nitrogen atoms at the same side of AlN sheet (AlN-2H) and (II) adsorption of hydrogen atoms on Aluminum and Nitrogen atoms at the two opposite sides of AlN sheet (H-AlN-H). The hydrogenated AlN nanosheet is semiconductor and its energy band-gap changes relative to the pristine AlN sheet, so that, the band-gap values were obtained as 3 and 4.3 eV for H-AlN-H and AlN-2H, respectively. Based on the calculated electronic properties, density functional calculations in the harmonic elastic deformation range are performed to obtain the mechanical elastic constants of pristine and fully hydrogenated AlN monolayer. Energetically, compared with the pristine AlN, hydrogenation AlN is more stable. Also, by calculating the formation energy of the structures AlN-2H and H-AlN-H, the results indicate that the structure of H-AlN-H is more stable than AlN-2H. In particular, it is found that the in-plane stiffness of hydrogenated AlN is significantly smaller than that of pristine AlN, so that, the in-plane stiffness was obtained as 82 N/m for H-AlN-H.