利用基于密度泛函理论(DFT)的第一性原理研究了O原子与Pd掺杂前后ZnO(0001)表面的相互作用机理。通过对模型表面六个高对称位吸附能的计算,发现O原子最有可能吸附于Pd掺杂表面的间隙位。从表面的态密度(density of states,DOS)及分波态密度(partial density of states,PDOS)分析结果可以看出,掺杂体系中费米能级附近出现的杂化峰是由O原子的p轨道电子和Pd原子的d轨道电子杂化引起的。掺杂表面的差分电荷密度反映出O原子与Pd原子之间存在大量电荷转移,说明掺入催化剂Pd有助于提高ZnO材料的气敏性能。最后,通过对挥发性有机化合物(VOC)气体的气敏测试验证了理论计算的结论。
By inserting an air cavity into a one-dimensional photonic crystal of LiF/GaSb, a tunable filter covering the whole visible range is proposed. Following consideration of the dispersion of the materials, through modulating the thickness of the air cavity, we demonstrate that a single resonant peak can shift from 416.1 to 667.3 nm in the band gap at normal incidence by means of the transfer matrix method. The research also shows that the transmittance of the channel can be maximized when the number of periodic Li F/Ga Sb layers on one side of the air defect layer is equal to that of the other side. When adding a period to both sides respectively, the full width at half maximum of the defect mode is reduced by one order of magnitude. This structure will provide a promising approach to fabricate practical tunable filters in the visible region with ultra-wide tuning range.
Xiaodan ZhaoYibiao YangZhihui ChenYuncai WangHongming FeiXiao Deng
Carbon cluster ion implantation is an important technique in fabricating functional devices at micro/nanoscale. In this work, a numerical model is constructed for implantation and implemented with a cuttingedge molecular dynamics method. A series of simulations with varying incident energies and incident angles is performed for incidence on silicon substrate and correlated effects are compared in detail. Meanwhile, the behavior of the cluster during implantation is also examined under elevated temperatures. By mapping the nanoscopic morphology with variable parameters, numerical formalism is proposed to explain the different impacts on phrase transition and surface pattern formation. Particularly, implantation efficiency(IE) is computed and further used to evaluate the performance of the overall process. The calculated results could be properly adopted as the theoretical basis for designing nano-structures and adjusting devices' properties.
Ye WeiShengbo SangBing ZhouXiao DengJing ChaiJianlong JiYang GeYuanliang HuoWendong Zhang
