Effect of fabrication errors on lateral super-resolution property of a three-zone pupil filter

Two models have been established using the basic definitions of super-resolution characteristic parameters for normalized spot size G_T and Strehl ratio S_T of a three-zone lateral super-resolution pupil filter with fabrication errors to quantitatively analyze the effect of these fabrication errors on the lateral super-resolution property. These new models established to describe the analytic relationship of G_Te and S_Te of a pupil filter with its fabrication errors and its transmission function A(ρ), phase function φ(ρ) and structural parameters directly relate the super-resolution parameters of a three-zone lateral super-resolution pupil filter to its fabrication errors to make the quantitative analyses of the effect of fabrication errors easier, thereby providing a theoretical basis for the analysis, design and fabrication of a three-zone lateral super-resolution pupil filter. The models established for G_Te and S_Te have been used to analyze the effect of the fabrication errors of a pupil filter on its super-resolution property with a three-zone phase-only pupil filter as an example.     

Comparison of CH4/H2 and C2H6/H2 inductively coupled plasma etching of ZnO

CH₄/H₂-based discharges are attractive for dry etching of single crystal ZnO because of their non-corrosive nature. We show that substitution of C₂H₆ for CH₄ increases the ZnO etch rate by approximately a factor of 2 both with and without any inert gas additive. The C₂H₆/H₂/Ar mixture provides a strong enhancement over pure Ar sputtering, in sharp contrast to the case of CH₄/H₂/Ar. The threshold ion energy for initiating etching is 42.4 eV for C₂H₆/H₂/Ar and 59.8 eV for CH₄/H₂/Ar. The etched surface morphologies were smooth, independent of the chemistry and the Zn/O ratio in the near-surface region was unchanged within experimental error after etching with both chemistries. The plasma etching improved the band-edge photoluminescence intensity and suppressed the deep level emission from the bulk ZnO under our conditions, due possibly to removal of surface contamination layer.     

Facile and rapid synthesis of zinc oxalate nanowires and their decomposition into zinc oxide nanowires

We describe a simple etching route for the fabrication of zinc oxalate nanowires, which can be easily converted to zinc oxide nanowires by a simple decomposition process. The zinc oxalate nanowires can be obtained in restricted conditions, for example, when a zinc foil is immersed in ethanolic or propanolic oxalic acid. Interestingly, the nanowires are not obtained in aqueous, methanolic or butanolic oxalic acid. The solubility of zinc oxalate in the solvents and position of favorable precipitation are primarily responsible for determining the morphology of zinc oxalate.     

Characterization of nuclear tracks by positron annihilation and gas permeation

The application of polymeric membrane in combination with metallic films can be used for gas purification in particular for hydrogen where the molecular size is very small. The affinity of hydrogen to certain metals assists the flow of hydrogen, although it restricts the permeation of other gases. However, the flow rate is very small in dense membranes. Attempts have been made to generate nuclear tracks in polymeric membranes to control the gas flow. These tracks can be characterized by positron lifetime spectroscopy and gas permeation measurements. The long lifetime of ortho-positronium gives the estimate of size of the track-free volume of the order of 0.25 nm. The nuclear tracks can be modified by a chemical etching process. The chemical etching normally takes place from both sides of the membrane. When the etched pits from both sides meet, a rapid increase in gas permeation is observed. The size of the nano opening of the track has been observed for two different gases hydrogen and carbon dioxide, which have a molecular size of 0.2 and 0.4 nm, respectively.     

Etching of gold nanorods: The effects of diameter on analytical performances

The diameters of gold nanorods have profound effects on the analytical performances of the corresponding etching based sensing system.     

Structural evolution of self-ordered alumina tapered nanopores with 100 nm interpore distance

We in-detail investigated the profile evolution processes of highly ordered alumina under the cyclic treatment of mild anodizing of aluminum foils in oxalic acid followed by etching in phosphoric acid. With the cyclic times increasing, the profiles of nanopores were gradually evolved into the parabola-like, trumpet-like and conical shape. Although the inserted etching itself nearly had no impact on the growth rate of the nanopores due to the rapid recovering of thinned barrier layer at the initial stage of next anodizing, overmuch etching could bring apparent side effects such as wall-breaking, thinning and taper-removing from the top down. The anodizing and etching kinetics and their synergetic effects in modulating different aspect ratios and open sizes of conical pores were studied systematically. These findings are helpful to tailor high-quality anodic alumina taper-pores with tunable profiles.     

The effect of etching time of porous silicon on solar cell performance

Porous silicon (PS) layers based on crystalline silicon (c-Si) n-type wafers with (1 0 0) orientation were prepared using electrochemical etching process at different etching times. The optimal etching time for fabricating the PS layers is 20 min. Nanopores were produced on the PS layer with an average diameter of 5.7 nm. These increased the porosity to 91%. The reduction in the average crystallite size was confirmed by an increase in the broadening of the FWHM as estimated from XRD measurements. The photoluminescence (PL) peaks intensities increased with increasing porosity and showed a greater blue shift in luminescence. Stronger Raman spectral intensity was observed, which shifted and broadened to a lower wave numbers of 514.5 cm⁻¹ as a function of etching time. The lowest effective reflectance of the PS layers was obtained at 20 min etching time. The PS exhibited excellent light-trapping at wavelengths ranging from 400 to 1000 nm. The fabrication of the solar cells based on the PS anti-reflection coating (ARC) layers achieved its highest efficiency at 15.50% at 20 min etching time. The I-V characteristics were studied under 100 mW/cm² illumination conditions.     

2+1维刻蚀模型生长表面等高线的共形不变性研究

为了更全面、有效地研究刻蚀模型(etching model)涨落表面的统计性质,基于Schramm Loewner Evolution(SLEκ)理论,对2+1维刻蚀模型饱和表面的等高线进行了数值模拟分析.研究表明,2+1维刻蚀模型饱和表面的等高线是共形不变曲线,可用Schramm Loewner Evolution理论进行描述,且扩散系数κ=2.70±0.04,属κ=8/3普适类.相应的等高线分形维数为df=1.34±0.01.     

光栅光阀器件的结构改进与制作工艺研究

根据光栅光阀的工作原理,在结构上对传统的光栅光阀器件进行了改进,分析了改进后光栅光阀器件的光学特性、结构特性,以及制作工艺流程.改进后的光栅光阀结构中硅基底上设有二氧化硅隔离层,隔离层上沉积无定形硅作为牺牲层,可动梁的材料是氮化硅,固定梁为蒸镀的金属铝层.通过离子刻蚀的方法刻蚀图形,用化学腐蚀方法掏空牺牲层得到所需桥梁状结构.研究表明改进后的器件黑区范围小,驱动电压较低,光学效率较高,具有潜在的应用前景.