In this paper, we report on a series of computational simulations on hydrogen bonding in two ice phases （Ih and Ic） using CASTEP with PW91 and RPBE exchange-correlation based on ab initio density functional theory. ...In this paper, we report on a series of computational simulations on hydrogen bonding in two ice phases （Ih and Ic） using CASTEP with PW91 and RPBE exchange-correlation based on ab initio density functional theory. The strength of the H-bond is correlated with intramolecular O-H stretching, and the energy splitting exists for both the H-bond and covalent O-H stretching. By analyzing the dispersion relationship of to（q）, we observe the separation of the longitudinal optic （LO） mode from transverse optic （TO） mode at the gamma point, seemingly interpreting the controversial two H-bond peaks in the vibrational spectrum of ice recorded by inelastic incoherent neutron scattering experiments. The test of ambient environment on phonon density of sates （PDOS） shows that the relaxed tetrahedral structure is the most stable structural configuration for water clusters.展开更多
The refractive index profiles of 3 MeV O^2＋ ion-implanted planar waveguides in lithium niobate are reconstructed based on etching and ellipsometry techniques. SRIM2003 code is used to simulate the damage distribution...The refractive index profiles of 3 MeV O^2＋ ion-implanted planar waveguides in lithium niobate are reconstructed based on etching and ellipsometry techniques. SRIM2003 code is used to simulate the damage distribution in waveguide. It is demonstrated that the index profile of this kind of waveguide, extending to several micrometres in depth, can be determined by etching in combination with following ellipsometric measurements. A good agreement is found between the simulated damage distributions in waveguide and the index profiles based on experimental data, and the width of refractive index barrier is wider than the result of SRIM2003.展开更多
文摘以P型<100>硅作为衬底,采用射频磁控溅射技术,在室温下制备了氮掺杂氧化铟锡锌薄膜晶体管(ITZO TFTs),研究了氮气流量对氧化铟锡锌薄膜晶体管结构、光学、电学特性以及稳定性的影响。实验结果表明:在不同氮气流量条件下制备的氧化铟锡锌薄膜均为非晶态,在可见光范围内的平均透过率均在90%左右,光学带隙数值在3.28~3.32 e V之间变化。在氮气流量为4 m L/min时制备的ITZO TFTs,有源层与栅极电介质界面处的界面态密度(N^(max)_s)仅为4.3×10^(11)cm^(-2),场效应迁移率(μ_(FE))为18.72 cm^2/(V·s),开关比(I_(on/off))为10~6,亚阈值摆幅(S)为0.39 V/dec,电学性能最优。栅极正偏压应力测试结果表明,该器件具有最强的稳定性。因此,适量的氮掺杂可有效地实现器件氧空位的钝化,降低器件的界面态密度,提高ITZO TFTs的电学性能及稳定性。
基金Project supported by the National Natural Science Foundation of China (Grant No.11075094)
文摘In this paper, we report on a series of computational simulations on hydrogen bonding in two ice phases （Ih and Ic） using CASTEP with PW91 and RPBE exchange-correlation based on ab initio density functional theory. The strength of the H-bond is correlated with intramolecular O-H stretching, and the energy splitting exists for both the H-bond and covalent O-H stretching. By analyzing the dispersion relationship of to（q）, we observe the separation of the longitudinal optic （LO） mode from transverse optic （TO） mode at the gamma point, seemingly interpreting the controversial two H-bond peaks in the vibrational spectrum of ice recorded by inelastic incoherent neutron scattering experiments. The test of ambient environment on phonon density of sates （PDOS） shows that the relaxed tetrahedral structure is the most stable structural configuration for water clusters.
基金Supported by the National Natural Science Foundation of China under Grant No 10735070. We would like to thank Professor Ke-Ming Wang at Shandong University for helpful discussion. We also thank Dr Hong-Ji Ma and Rui Nie at Peking University for their help in ion implantation.
文摘The refractive index profiles of 3 MeV O^2＋ ion-implanted planar waveguides in lithium niobate are reconstructed based on etching and ellipsometry techniques. SRIM2003 code is used to simulate the damage distribution in waveguide. It is demonstrated that the index profile of this kind of waveguide, extending to several micrometres in depth, can be determined by etching in combination with following ellipsometric measurements. A good agreement is found between the simulated damage distributions in waveguide and the index profiles based on experimental data, and the width of refractive index barrier is wider than the result of SRIM2003.
