First-Principles Study of Intrinsic Point Defects of Monolayer GeS

The properties of six kinds of intrinsic point defects in monolayer GeS are systematically investigated using the“transfer to real state”model,based on density functional theory.We find that Ge vacancy is the dominant intrinsic acceptor defect,due to its shallow acceptor transition energy level and lowest formation energy,which is primarily responsible for the intrinsic p-type conductivity of monolayer GeS,and effectively explains the native p-type conductivity of GeS observed in experiment.The shallow acceptor transition level derives from the local structural distortion induced by Coulomb repulsion between the charged vacancy center and its surrounding anions.Furthermore,with respect to growth conditions,Ge vacancies will be compensated by fewer n-type intrinsic defects under Ge-poor growth conditions.Our results have established the physical origin of the intrinsic p-type conductivity in monolayer GeS,as well as expanding the understanding of defect properties in lowdimensional semiconductor materials.     

Effect of Tensor Force on the Halo Structure of ^29Ne and ^31Ne

The structure of Ne isotopes has been investigated by using deformed Skyrme-Hartree-Fock （SHF） method and BCS approximation. Especially the effect of tensor force on the halo structure of 29Ne and 31Ne is discussed. To this end, the tensor contributions are considered to the energy density function and the single particle potential in SHF theory. For comparison, four Skyrme interactions are used： SLy5 and SGII without tensor force, and SLy5＋T and SGII＋ T with tensor force. The results indicate that the inclusion of tensor force shows a more pronounced halo structure for 31Ne.     

Optical Ring-Resonator Modulator Based on 0.8 μm CMOS Technology

Optical ring-resonator-based modulators are fabricated on the silicon-on-insulator material through the mature commercial 0.8μm complementary metal oxide semiconductor foundry. The device configuration is based on a single ring resonator coupled to one bus waveguide. The waveguide widths are about 1 μm. The p-i-n junctions are employed to inject currents. The experimental result shows that the ring resonators with the quality factor of above 40000 are obtained. The maximum extinction ratio of the modulators is larger than 10dB. The speed is tens of nanoseconds, and the corresponding injected current is smaller than 10 mA.     

Efect of Tensor Force on the Halo Structure of ~(29)Ne and ~(31)Ne

The structure of Ne isotopes has been investigated by using deformed Skyrme–Hartree–Fock(SHF)method and BCS approximation.Especially the efect of tensor force on the halo structure of 29Ne and 31Ne is discussed.To this end,the tensor contributions are considered to the energy density function and the single particle potential in SHF theory.For comparison,four Skyrme interactions are used:SLy5 and SGII without tensor force,and SLy5+T and SGII+T with tensor force.The results indicate that the inclusion of tensor force shows a more pronounced halo structure for31Ne.