摘要
High carrier mobility and a direct semiconducting band gap are two key properties of materials for elec- tronic device applications. Using first-principles calculations, we predict two types of two-dimensional semiconductors, ultrathin GeAsSe and SnSbTe nanosheets, with desirable electronic and optical prop- erties. Both GeAsSe and SnSbTe sheets are energetically favorable, with formation energies of -0.19 anti -0.09 eV/atom, respectively, and have excellent dynamical and thermal stability, as determined by phonon dispersion calculations and Born-Oppenheimer molecular dynamics simulations. The rel- atively weak interlayer binding energies suggest that these monolayer sheets can be easily exfoliated from the bulk crystals. Importantly, monolayer GeAsSe and SnSbTe possess direct band gaps （2.56 and 1.96 eV, respectively） and superior hole mobility （- 20 000 cm2.V-1.s-1）, and both exhibit notable absorption in the visible region. A comparison of the band edge positions with the redox potentials of water reveals that layered GeAsSe and SnSbTe are potential photocatalysts for water splitting. These exceptional properties make layered GeAsSe and SnSbTe promising candidates for use in future high-speed electronic and optoelectronic devices.
High carrier mobility and a direct semiconducting band gap are two key properties of materials for elec- tronic device applications. Using first-principles calculations, we predict two types of two-dimensional semiconductors, ultrathin GeAsSe and SnSbTe nanosheets, with desirable electronic and optical prop- erties. Both GeAsSe and SnSbTe sheets are energetically favorable, with formation energies of -0.19 anti -0.09 eV/atom, respectively, and have excellent dynamical and thermal stability, as determined by phonon dispersion calculations and Born-Oppenheimer molecular dynamics simulations. The rel- atively weak interlayer binding energies suggest that these monolayer sheets can be easily exfoliated from the bulk crystals. Importantly, monolayer GeAsSe and SnSbTe possess direct band gaps （2.56 and 1.96 eV, respectively） and superior hole mobility （- 20 000 cm2.V-1.s-1）, and both exhibit notable absorption in the visible region. A comparison of the band edge positions with the redox potentials of water reveals that layered GeAsSe and SnSbTe are potential photocatalysts for water splitting. These exceptional properties make layered GeAsSe and SnSbTe promising candidates for use in future high-speed electronic and optoelectronic devices.
基金
This work was supported by the National Natural Science Foundation of China （Grant No. 11574040）, the Fundamental Research Funds for tile Central Universities of China （Grant Nos. DUT16-LAB01 and DUT17LAB19）. Y. G. was supported by China Scholarship Council （CSC, Grant No. 201706060138）. X. C. Z. was supported by the National Science Foundation （NSF） through the Nebraska Materials Research Science and Engineering Center （MRSEC） （Grant No. DMR- 1420645）. We acknowledge the computing resource from the Su- percomputing Center of Dalian University of Technology and the University of Nebraska Holland Computing Center.
