In this work, we studied the effect of different pH values on morphology, band gap and photoluminescence (PL) properties of Eu³⁺/Tb³⁺ co-doped ZnO prepared by coprecipitation method. Experimental results show that alkaline condition is more favorable for the doping of Eu³⁺ and Tb³⁺ ions which reduce the band gap and increases the PL intensity of UV emission (385 nm) and visible emission (400—600 nm) of ZnO. Gaussian deconvolution PL spectra show that the defects on the surface of ZnO are decreased when it is synthesized under alkaline conditions. Furthermore, both the intrinsic orange emission of Eu³⁺ ions (611 nm) and the intrinsic green emission of the Tb³⁺ ions (495 nm) of ZnO in this case are obtained at the same time. High intensity green and orange emission indicates that Eu³⁺/Tb³⁺ co-doped ZnO is a promising PL material and has potential in emission devices.

The influence of polyvinylpyrrolidone (PVP) and monoethanolamine (MEA) as surfactants on photoluminescence (PL) of Eu-doped ZnO (ZnO:Eu) has been studied. X-ray diffraction (XRD) results show that there are more Eu³⁺ ions to replace Zn²⁺ ions into ZnO lattice for ZnO:Eu in the presence of surfactant MEA. From the spectral analysis for ZnO:Eu with different surfactants by Gaussian deconvolution, it can be seen that the use of MEA as a surfactant affects the energy transfer from ZnO host to Eu³⁺ ions and leads to three new emission peaks, including UV emission (389 nm), violet emission (411 nm) and green emission (506 nm).

A series of MoS₂/ZnO compound photocatalysts with different mass ratios were successfully prepared by hydrothermal method. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and UV-vis absorption were used to characterize the prepared MoS₂/ZnO photocatalysts. It was proved that the combination of MoS₂ and ZnO can increase the content of oxygen vacancies on surface of ZnO, thus improving the light absorption capacity in visible light region and reducing the band gap of ZnO. And the photocatalytic performance of ZnO was improved. Experimental results show that the MoS₂/ZnO (3 wt%) compound has the highest degradation rate for methylene blue (MB) under visible light, which means that it has the best photocatalytic activity among all the prepared samples.

Au nanoparticles doped TiO2 nanowires (NWs) arrays with an average diameter of 100 nm were synthesized through a facile solvothermal method. Thereafter, metal/semiconductor/metal (MSM) structured detectors with Ag electrodes were fabricated on these NWs. The ultraviolet (UV) sensing characteristics of pure TiO2 and Au-doped ones (Au-TiO2) were investigated. Compared with pure TiO2, the Au-TiO2 NWs based device shows a much lower dark current of 1.5 nA at 3 V bias. The low dark current mechanism might be due to the promoted directional transmission of carriers induced by Au doping. The photoresponse is nearly one order of magnitude under 360 nm monochromatic illumina-tion. The Au-TiO2 NWs detector with simple fabrication process, low noise and good overall performance provides a broad way in fabricating UV imaging arrays.

In this study, we present a facile method for the fabrication of ZnO/AuNPs hexagonal wurtzite structure by sol-gel method. Transmission electron microscope (TEM) results indicate that the synthesized AuNPs have good round shape and uniform size with an average diameter of 15 nm. Scanning electron microscope (SEM) results show that the pre-pared ZnO/AuNPs nanocomposites are uniform spheroidal nanoparticles with sizes in diameter from 60 nm to 100 nm. The presence of Zn, Au and O elements in those samples is determined by X-ray photoelectron spectroscopy (XPS) analysis. The investigation of photocatalytic ability shows that the ZnO/AuNPs (8 mL) achieve complete degradation of methylene blue (MB) under UV irradiation with 65 min. We can conclude that the presence of AuNPs hybrid ZnO can strongly enhance the photocatalytic performance of MB compared to pure ZnO, which may be attributed to the larger specific surface area and surface plasmon resonance (SPR) effect of AuNPs hybrid ZnO nanocomposites. This method may provide a new way to improve ZnO photocatalysis for water cleaning application.

In this work, indium nitride (InN) films were successfully grown on porous silicon (PS) using metal oxide chemical vapor deposition (MOCVD) method. Room temperature photoluminescence (PL) and field emission scanning electron microscopy (FESEM) analyses are performed to investigate the optical, structural and morphological properties of the InN/PS nanocomposites. FESEM images show that the pore size of InN/PS nanocomposites is usually less than 4 μm in diameter, and the overall thickness is approximately 40 μm. The InN nanoparticles penetrate uniformly into PS layer and adhere to them very well. Nitrogen (N) and indium (In) can be detected by energy dispersive spectrometer (EDS). An important gradual decrease of the PL intensity for PS occurs with the increase of oxidation time, and the PL intensity of PS is quenched after 24 h oxidization. However, there is a strong PL intensity of InN/PS nanocomposites at 430 nm (2.88 eV), which means that PS substrate can influence the structural and optical properties of the InN, and the grown InN on PS substrate has good optical quality.

CdS nanocrystals have been successfully grown on porous silicon (PS) by sol-gel method. The plan-view field emission scanning electron microscopy (FESEM) shows that the pore size of PS is smaller than 5 μm in diameter and the agglomerates of CdS are broadly distributed on the surface of PS substrate. With the increase of annealing time, the CdS nanoparticles grow in both length and diameter along the preferred orientation. The cross-sectional FESEM images of ZnO/PS show that CdS nanocrystals are uniformly penetrated into all PS layers and adhere to them very well. photoluminescence (PL) spectra demonstrate that the intensity of PL peak located at about 425 nm has almost no change after the annealing time increases. The range of emission wavelength of CdS/PS is from 425 nm to 455 nm and the PL intensity is decreasing with the annealing temperature increasing from 100 °C to 200 °C.

利用Advanced Physical Models of Semiconductor Devices (APSYS)理论对比研究了InGaN/AlInGaN 和 InGaN/GaN多量子阱作为有源层的InGaN基发光二极管的结构和电学特性。与InGaN/GaN 基LED 中GaN作为垒层材料相比，在AlInGaN材料体系中，通过调节AlInGaN中Al和In的组分可以优化器件的性能。当InGaN阱层材料中In组分为8%时，可以实现无应力的In0.08Ga0.92N/AlInGaN基 LED。在这种无应力结构中可以进一步降低大功率LED的“效率下降”(Effciency droop)问题。理论模拟结果显示，四元系AlInGaN作为垒层可以进一步减少载流子泄露，增加空穴注入效率，减少极化场对器件性能的影响。在In0.08Ga0.92N /AlInGaN量子阱中的载流子浓度、有源层的辐射复合率、电流特性曲线和内量子效率等方面都优于InGaN/GaN基LED。无应变AlInGaN垒层代替传统的GaN垒层后，能够得到高效的发光二极管，并且大电流注入下的“效率滚降”问题得到改善。

We propose a compact dual-band bandpass filter (BPF) based on one-dimensional porous silicon (PS) photonic crystal by electrochemical etching. By inserting three periods of high and low reflective index layers in the center of porous silicon microcavity (PSM), two sharp resonant peaks appear in the high reflectivity stop band on both sides of the resonance wavelength. Through simulation and experiment, the physical mechanisms of the two resonance peaks and the resonance wavelength are also studied. It is found that the resonance wavelength can be tuned only by adjusting the effective optical thickness (EOT) of each PS layer, in which different resonance wavelengths have different widths between the two sharp resonance peaks. Besides, the analysis indicates that oxidization makes the blue shift become larger for high wavelength than that for low wavelength. Such a fabricated BPF based on PS dual-microcavity is easy to be fabricated and low cost, which benefits the application of integrated optical devices.

利用阴影在色调亮度饱和度颜色空间中低亮度、高色调和高饱和度的特性, 对高分辨率遥感影像做过分割处理, 并将影像从红、绿、蓝颜色空间转换到色调、亮度、饱和度颜色空间, 利用色调、亮度、饱和度三个分量构造一组能够更好区分阴影和其他地物的新型阴影探测指标.对阴影指标做面向对象处理, 得到一种保持空间几何形状的阴影指标结果；根据最大类间方差法计算得到最佳阈值, 并做直方图阈值分割, 最终得到阴影探测结果.实验结果表明, 该方法可以有效地将阴影与其他地物分离开来.