First principles study of doped gallium nanostructures

Abstract

In the present work, doped gallium nanostructures have been analysed in the framework of the Density Functional Theory. The structural, electronic and magnetic properties of small gallium clusters and cobalt doped gallium nanoclusters using spin polarized density functional theory. The calculation of binding energy per atom, second order differences of total energies, and fragmentation energies of equilibrium geometries of the host Gan+1 and doped GanCo (n=1-12) clusters are done which suggest that the doped clusters are more stable than pure Ga clusters; Ga3Co, Ga5Co and Ga8Co clusters are exceptionally stable. Doping with Co also varies energy band gap and affects the magnetic moments of clusters. The investigation of the structural, electronic,mechanical and magnetic properties of gallium nitride nanosheet (GaNs) doped with Mn atoms and Mn intercalated GaN homobilayer sheets has been done. Doping makes the sheets more stable and introduces the ferromagnetic behaviour. Four different sites of doping are chosen and the variation in electronic behaviour of sheets is observed, however magnetic and mechanical properties remain unaltered on varying the site of doping. The conductivity is found to be greatly dependent upon the doping site which may be attributed to the variation in the energy band gap (Eg) of the structures. Due to be ferromagnetic nature of doped sheets, they find their future applicability in perspective of magnetic data storage and optoelectronic devices. On investigating the elastic properties of GaNs and GaNs-Mn it is concluded that the energy band gap could be possibly engineered in different ways upon application of in- plain biaxial strain and external electric field. With increase in the magnitude of strain these direct semiconductor nanosheets get transformed into indirect semiconductor, then into semimetals and finally they metalize. In our calculations, the ultimate tensile strength (UTS) of the monolayer and homobilayer sheets comes out to be 23.9 GPa and 48 GPa respectively.