Fluorination induced half metallicity in two-dimensional few zinc oxide layers

First-principles calculations of the BeO monolayer with chemical functionalization

Recently, extensive experimental and theoretical studies on two-dimensional materials have attracted enormous interest in exploring the properties of these materials by decorating their surfaces. In the present work, we present a detailed investigation of the structures, and electronic and magnetic properties of pristine, hydrogenated, and fluorinated BeO monolayers using the ab initio density functional theory approach. Structurally, the most stable adsorption sites are directly above the host Be atom for half-hydrogenation, above the middle of the Be-O bond for half-fluorination, and directly above the host Be atom and below the host O atom for full-hydrogenation and full-fluorination. Moreover, the electronic and magnetic properties of the BeO monolayer exhibit high sensitivity to chemical functionalization: half-hydrogenation induces nonmagnetic-magnetic transition and the reduction of the band gap reaches about 75%. Full-hydrogenation results in metallization of the BeO monolayer. Half-fluorination makes the BeO monolayer a 100% spin polarized material regardless of the adsorption site. However, depending on different adsorption sites, full-fluorination can produce either magnetically half-metallic or nonmagnetic semiconductor structures. These results demonstrate that the tunability of the electronic and magnetic properties of the BeO monolayer can be realized by chemical functionalization for future nano-electronic and spintronic device applications.

Effects of the number of layers on the vibrational, electronic and optical properties of alpha lead oxide

We have investigated the effects of the number of layers on the structure, vibrational, electronic and optical properties of α-PbO using first principles calculations. Our calculations have indicated that ultrathin films of α-PbO (such as 3 nm thickness) could be excellent candidates for solar cells.

Chemical functionalization of the ZnO monolayer: structural and electronic properties

Two-dimensional zinc oxide (ZnO) materials have been extensively investigated both experimentally and theoretically due to their novel properties and promising applications in optoelectronic and spintronic devices; however, how to tune the electronic property of the ZnO monolayer is still a challenge. Herein, employing the first-principles calculations, we explored the effect of chemical functionalization on the structural and electronic properties of the ZnO monolayer. The results demonstrated that the hydrogenated-, fluorinated- or Janus-functionalized ZnO monolayers were thermodynamically and mechanically stable except for the fully hydrogenated ZnO monolayer. The band gap of the ZnO monolayer could be effectively modulated by hydrogenation or fluorination, which varied from 0 to 2.948 eV, as obtained by the PBE functional, and from 0 to 5.114 eV, as obtained by the HSE06 functional. In addition, a nonmagnetic metal → nonmagnetic semiconductor transition was achieved after hydrogenation, whereas a transition from a magnetic half-metal to nonmagnetic semiconductor occurred after fluorination of the ZnO monolayer. These results demonstrate that tunability of the electronic properties of the ZnO monolayer can be realized by chemical functionalization for future nanoelectronic device applications.

After hydrogenation or fluorination, the band gap of the ZnO monolayer can be effectively modulated, and a nonmagnetic metal or magnetic half-metal → non-magnetic semiconductor transition can be achieved.

Tuning electronic and magnetic properties of GaN nanosheets by surface modifications and nanosheet thickness

(a and b) Atomic and band structures of 2-F-GaN NS, and (c) electronic and magnetic properties of different GaN NSs.

Electronic structure engineering in chemically modified ultrathin ZnO nanofilms via a built-in heterointerface

The electronic properties of chemically modified ZnO ultrathin films with a built-in heterointerface are investigated on the basis of first-principles calculations.

Stability of graphitic-like zinc oxide layers under carriers doping: a first-principles study

Although theoretical works have demonstrated that (0001) polar films of wurtzite (WZ) ZnO automatically transform into graphitic-like (GP) structures, the experimental realization of GP ZnO is limited to a thickness of several atomic layers. Here, using first-principles calculations, we demonstrated that the stability of GP ZnO is closely related to the concentration of near-free carriers. Our results show that the doped carriers, originating from the rich oxygen vacancies, can effectively screen the polar field, and stabilize the WZ structure. Thus, in order to obtain GP ZnO layers with much thicker films, it is necessary to reduce the near-free carrier concentration.

Tuning electronic and magnetic properties of wurtzite ZnO nanosheets by surface hydrogenation

Through density functional theory computations, we systematically investigated the structural, electronic, and magnetic properties as well as the relative stabilities of fully and partially hydrogenated ZnO nanosheets. Unlike bare ZnO nanosheets terminating with polar {0001} surfaces, their hydrogenated counterparts preserve the initial wurtzite configuration. Full hydrogenation is more favorable energetically for thinner ZnO nanosheets, whereas semihydrogenation at O sites is preferred for thicker ones. Moreover, semiconductor --> half-metal --> metal transition occurs with nonmagnetic --> magnetic transfer upon adopting surface hydrogenation and increasing sheet thickness. The predicted diverse and tunable electronic and magnetic properties endow ZnO nanosheets potential applications in electronics and spintronics.