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排序方式: 共有340条查询结果,搜索用时 15 毫秒
31.
32.
Photoconductive CdSe doped with (1–5 wt%) of Cu was fabricated using the vacuum evaporation technique for thin-film preparation followed by vacuum annealing at 350°C under an argon environment for doping with copper. The electrical and detection properties as a function of Cu content were studied. It was found that the gain coefficient was increased with an increase in the Cu impurity concentration and better results were obtained for a CdSe:Cu detector of 5 wt% concentration, which showed a gain coefficient of up to 8.87×103 for white illumination 1000 Lux. This value is much greater than the published value for pure CdSe film, possibly due to the sensitizing action of Cu centers. Additional weak but well resolved features were observed in the high-energy region of the curve depicting gain coefficients as a function of wavelength characteristics. These peaks were attributed to the 3D transition of Cu from deep levels in the valence band. 相似文献
33.
Single crystals of CdSe were grown by using seeded oriented temperature gradient solution zoning (STGSZ) method with the sizes of 20 mm in diameter and 80 mm in length. The crystals were characterized with X-ray diffraction, transmission spectrophotometer and infrared microscope. The transmission spectra showed that the infrared transmission is above 65% and the mean absorption was 0.01-0.04 cm-1 in the range of 2.5-20 μm.With 2.797 μm Cr, Er:YSGG laser as pumping source,experiments of optical parametric oscillator (OPO) were performed by using fabricated 5mm×5mm×30mm device crystal. The signal and idler wavelengths and the output average power were respectively 4.3 μm, 8 μm and 400 μJ. Optical-to-optical conversion efficiency was obtained by 12%. 相似文献
34.
CdSe/ZnS量子点光纤纤芯基底的研究 总被引:1,自引:0,他引:1
量子点光纤正逐渐成为光通信领域的研究热点。首先介绍了CdSe/ZnS量子点掺杂光纤的发展历史,随后给出两种不同纤芯基底材料的CdSe/ZnS量子点掺杂光纤的制备方法,并对它们的光谱特性及发射峰值增益进行了分析比较,最后分析得出适合CdSe/ZnS量子点掺杂光纤的纤芯基底材料。CdSe/ZnS量子点掺杂光纤基底材料的研究对其他量子点光纤的研制具有一定的借鉴作用。 相似文献
35.
Andrea Fasoli Alan Colli Faustino Martelli Simone Pisana Ping Heng Tan Andrea C. Ferrari 《Nano Research》2011,4(4):343-359
We present temperature and power dependent photoluminescence measurements on CdSe nanowires synthesized via vapor-phase with
and without the use of a metal catalyst. Nanowires produced without a catalyst can be optimized to yield higher quantum efficiency,
and narrower and spatially uniform emission, when compared to the catalyst-assisted ones. Emission at energies lower than
the band-edge is also found in both cases. By combining spatially-resolved photoluminescence and electron microscopy on the
same nanowires, we show that catalyst-free nanowires exhibit a low-energy peak with sharp phonon replica, whereas for catalyst-assisted
nanowires low-energy emission is linked to the presence of nanostructures with extended morphological defects.
相似文献
36.
J. -O. Ndap C. I. Rablau K. Morrow O. O. Adetunji V. A. Johnson K. Chattopadhyay R. H. Page A. Burger 《Journal of Electronic Materials》2002,31(7):802-805
The maximum optical-absorption cross section of Cr2+ ions was evaluated from near-infrared (NIR) absorption spectroscopy and direct measurements of the chromium concentration
in Cr2+:CdSe crystals. The emission lifetime of the excited state, 5E, of Cr2+ was measured as a function of Cr2+ concentration in the 2×1017 −2×1018 ions/cm3 range and as a function of temperature from 77–300 K. Lifetime values were as high as ∼6 μs in the 77–250 K range and decreased
to ∼4 μs at 300 K because of nonradiative decays. Assuming that most of the Cr dopant is in the Cr2+ state, an optical-absorption cross section σa of (1.94±0.56) × 10−18 cm2 was calculated. Implications for laser performance are discussed. 相似文献
37.
Photovoltaic performance of semiconductor-liquid junction solar cell using electro-codeposited thin filmn-CdSe is found to improve significantly by proper surface treatments. The solid state parameters of annealed films are calculated
and compared with those of unannealed film-based cells. Chemical etching is found to improve short circuit current and fill
factor whereas photoelectrochemical etching technique improves the stability of photoanode in polysulphide electrolyte. Annealing
promotes incipient fusion of small crystallites, thus reducing the grain boundaries which are known to act as recombination
centres for minority carriers and trapping centre for majority carriers. The conversion efficiency and stability are found
to improve by chemical etching of the semiconductor layer because chemical etching pins Fermi level of CdSe photoanode and
promotes exchange current density. 相似文献
38.
A novel method for the preparation of water-soluble and small-size CdSe quantum dots 总被引:2,自引:0,他引:2
A novel method for the preparation of water-soluble and small-size CdSe quantum dots has been reported under high-intensity ultrasonic irradiation. The as-prepared products have been characterized by absorption spectra, X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). 相似文献
39.
对用原子层外延方法,在[001]晶向GaAs衬底上生长的[(Cdse)m(Znse)n]p-ZnSe应变量子阱结构,在10~300K温度范围内测量了喇曼散射光谱,观察到两种类ZnSeLO声子限制模.利用改变样品温度和入射光能量实现了共振喇曼散射,观察到高达7阶的类ZnSeLO声子模.并讨论了多声子喇曼散射和热萤光过程的区别. 相似文献
40.