Enhancement of optical properties of CdSe pillars fabricated by the combination of electron-beam lithography and electrochemical deposition

Chen, Yeng-Long; Chen, C. C.; Jeng, Jyh‐Yuan; Chen, Y. F.

doi:10.1063/1.1782251

Cited by 11 publications

(8 citation statements)

References 14 publications

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“…[ 22 ] The giant enhancement of the PL intensity over a range of wavelength due to optical resonant cavity formation, similar to this work, has also been reported before, for example, in annealed siliconon-insulator structures ( ≈ 37 times in intensity), [ 23 ] Er-doped Si/ SiO 2 reonant cavities ( ≈ 5 times), [ 24 ] and the CdSe pillars fabricated by the combination of electron beam lithography and electrochemical deposition. [ 25 ] Based on the above discussion, the requirements for ultraintense luminescence in core/shell 1D nanostructures may be summarized as follows: 1) the uncoated 1D nanostructures should have faceted surfaces as well as luminescence and the core material should have a suffi ciently large E g and 2) the shell layer should have not only an optimal thickness satisfying the condition for optical resonant cavity formation, but also a good thickness uniformity.…”

Section: Doi: 101002/adma201004266mentioning

confidence: 99%

Ultraintense Luminescence in Semiconducting‐Material‐Sheathed MgO Nanorods

et al. 2011

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One-dimensional (1D) nanostructures, such as nanowires, nanorods, nanobelts, nanoribbons, nanoneedles, and nanotubes, have attracted considerable attention due to their unique and fascinating properties as well as their potential technological applications. [ 1 ] In particular, 1D nanostructures are emerging as powerful building blocks for nanoscale photonic devices such as light-emitting diodes, photodiodes, lasers, active waveguides, and integrated electro-optic modulator structures because of their higher luminescence effi ciency. [ 2 , 3 ] The luminescence property of 1D nanostructures can be further enhanced by creating core/shell heterostructures. [4][5][6] Ultraviolet photoluminescence (PL) enhancement by sheathing ZnO 1D nanostructures with a larger bandgap material such as ZnS, [ 7 ] SnO 2 , [ 8 ] MgO, [ 9 ] or Al 2 O 3[ 10 ] has recently been demonstrated. This technique was reported to increase the emission intensity by a few times due to the quantum confi nement effect of the photogenerated carriers in the ZnO cores. [7][8][9][10] In the present paper, we report that sheathing well-faceted MgO nanorods with a semiconductor fi lm with an optimal thickness resulted in ultraintense luminescence characteristic of the sheath material and its origin is discussed. The intensity of the blue-green emission from the MgO-core/TiO 2 -shell nanostructures with a specifi c shell layer thickness ( ≈ 20 nm) was ≈ 220 times higher than that of the original orange emission from the MgO nanorods. In addition, we discuss the requirements and design of the MgO-core/ semiconductor-shell nanorod system for ultraintense luminescence in other wavelength ranges. Figure 1 a shows the scanning electron microscopy (SEM) images of the MgO-core/TiO 2 -shell nanorods synthesized by the thermal evaporation of Mg 3 N 2 powders at 900 ° C for 1 h in an oxidative atmosphere and the metal organic chemical vapor deposition (MOCVD) of TiO 2 at 350 ° C for 2 h. Recently, MgO 1D nanostructures were synthesized successfully using a range of techniques including sol-gel process; [ 11 ] thermal evaporation of MgO, [ 12 ] MgB 2 , [ 13 ] or Mg 3 N 2 powders; [ 14 ] and pulsed laser deposition. [ 15 ] Of these techniques, the MgO 1D nanostructures with facetted surfaces are known to be grown most easily by the thermal evaporation of Mg 3 N 2 powders. Statistical analysis of many SEM images of the core/shell nanorods revealed widths ranging from 60 to 180 nm and lengths ranging from 3 to 5 μ m. The SEM image in Figure 1 b clearly displays the geometrical confi guration of a typical core/shell nanorod with a square cross-section and faceted surfaces. The enlarged SEM image of a typical core/shell nanorod (inset in Figure 1 b) showed that a globular particle did exist at the tip of the nanorod, suggesting that the nanorods were grown via a vapor-liquid-solid mechanism. Five elements including Mg, Ti, O, Cu, and C were detected in the energy dispersive X-ray (EDX) spectra (Figure 1 c) of these core/shell nanorods. Of these elements, Mg, Ti, and O wer...

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Section: Doi: 101002/adma201004266mentioning

confidence: 99%

Ultraintense Luminescence in Semiconducting‐Material‐Sheathed MgO Nanorods

et al. 2011

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“…Note that such an effect, called random laser action, was earlier observed in ZnO and GaN powders [11]. Besides, enhancement of photoluminescence was recently reported in CdSe pillars fabricated by the combination of electron beam lithography and electrochemical deposition [12]. The PL spectrum of porous CdSe regions exhibiting strong scattering of light is illustrated in figure 4 (curve A).…”

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confidence: 65%

Porosity-induced gain of luminescence in CdSe

Monaico

Ursaki

Urbieta

et al. 2004

Semicond. Sci. Technol.

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Porous CdSe layers have been produced by anodic etching of crystalline substrates in a HCl solution. Anodization under in situ UV illumination resulted in the formation of uniformly distributed parallel pores with a diameter of 30 nm, stretching perpendicularly to the initial surface. At the same time, pronounced nonuniformities in the spatial distribution of pores were evidenced in samples subjected to anodic etching in the dark. Gain of luminescence was observed in some porous regions and attributed to the formation of ring microcavities for light in the porous network.

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“…Various procedures have been proposed and applied to the preparation of nanostructures, such as electronbeam lithography [6], chemical vapor deposition [7], and template method [8]. Among the methods reported, the template synthesis method pioneered by Martin has been widely adapted because of its many interesting and useful features [9].…”

Section: Introductionmentioning

confidence: 99%