• Title, Summary, Keyword: Photoluminescence

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Improved Photoluminescence from Light-Emitting Silicon Material by Surface Modification

  • 김동일;이치우
    • Bulletin of the Korean Chemical Society
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    • v.16 no.11
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    • pp.1019-1023
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    • 1995
  • A light-emitting silicon material was prepared by electrochemical etching of n-Si single crystal wafers in a solution of hydrofluoric acid and ethanol. Visible photoluminescence from the silicon was inhomogeneous and decayed rapidly in the ambient laboratory conditions or with photoirradiation. Substantial improvements in photoluminescence which include little-dependent luminescence peak energy with excitation energy variation and longer-lasting room temperature visible photoluminescence were achieved when the surface of photoluminescent silicon material was derivatized with the surface modifier of octadecylmercaptan. Surface modification of the photoluminescent silicon was evidenced by the measurements of contact angles of static water drops, FT-IR spectra and XPS data, in addition to changed photoluminescence. Similar improvements in photoluminescence were observed with the light-emitting silicon treated with dodecylmercaptan, but not with octadecane. The present results indicate that sulfurs of octadecylmercaptans or dodecylmercaptans appear to coordinate the surface Si atoms of LESi and perturb the surface states to significantly change the luminescent characteristics of LESi.

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The Effect of Temperature on the Photoluminescence Properties of the InZnP/ZnSe/ZnS (Core/Multishell) Quantum Dots (온도에 따른 InZnP/ZnSe/ZnS (핵/다중껍질) 양자점의 형광 특성 변화)

  • Son, Min Ji;Jung, Hyunsung;Lee, Younki;Koo, Eunhae;Bang, Jiwon
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.31 no.7
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    • pp.443-449
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    • 2018
  • We investigated the temperature-dependent photoluminescence spectroscopy of colloidal InZnP/ZnSe/ZnS (core/shell/shell) quantum dots with varying ZnSe and ZnS shell thickness in the 278~363 K temperature range. Temperature-dependent photoluminescence of the InZnP-based quantum dot samples reveal red-shifting of the photoluminescence peaks, thermal quenching of photoluminescence, and broadening of bandwidth with increasing temperature. The degree of band-gap shifting and line broadening as a function of temperature is affected little by shell composition and thickness. However, the thermal quenching of the photoluminescence is strongly dependent on the shell components. The irreversible photoluminescence quenching behavior is dominant for thin-shell-deposited InZnP quantum dots, whereas thick-shelled InZnP quantum dots exhibit superior thermal stability of the photoluminescence intensity.

Enhancing photoluminescence of Au - TiO2 nanoparticles using Drude model

  • Dang, Diem Thi-Xuan;Vu, Thi Hanh Thu
    • Journal of IKEEE
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    • v.21 no.3
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    • pp.288-296
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    • 2017
  • The enhancement of photoluminescence of Au-$TiO_2$ nanoparticles by surface plasmon resonance has been studied extensively by experiment in recent years. For the purpose of optimizing the photoluminescence property of Au-$TiO_2$ nanoparticles, the manufacturing parameters related to the Au nanoparticles and $TiO_2$ nanoparticles need to be considered. In this paper, Drude model and Maier's effective volume method are used to analyze the variation of the metal nanoparticle radius, separation between metal nanoparticle and dielectric molecule, and total absorption cross-section with original radiative efficiency on the photoluminescence property of Au-$TiO_2$ nanoparticles. The results show that to obtain the optimized enhancement factor for photoluminescence process, the size of Au nanoparticle is about 13 - 20 nm, the separation between Au nanoparticle and $TiO_2$ molecule is about 5 -15 nm, the total absorption cross-section of $TiO_2$ molecules is about $1-100nm^2$ and the original radiative efficiency of $TiO_2$ molecule is weak about 0.001- 0.1. With these fabrication parameters, the photoluminescence property of Au-$TiO_2$ nanoparticles can be enhanced several thousand times compared to traditional $TiO_2$ nanoparticles.

A New Approach to Synthesis and Photoluminescence of Silicon Nanoparticles

  • Kim, Beomsuk
    • Journal of the Chosun Natural Science
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    • v.2 no.1
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    • pp.28-31
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    • 2009
  • We describe the synthesis and characterization of silicon nanoparticles prepared by the soluton reduction of SiCl4. These reactions produce Si nanoparticles with surfaces that are covalently terminated. The resultant organic derivatized Si nanoparticles as well as a probable distribution of Water-soluble Si nanoparticles are observed and characterized by photoluminescence(PL) spectroscopy. This work focuses originally on the organic- and water-soluble silicon nanoparticles in terms of the photoluminescence. Further this work displays probably the first layout of hydrogen terminated Si nanoparticles synthesized in solution at room temperature.

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Detection of Nitroaromatic Compounds with Functionalized Porous Silicon Using Quenching Photoluminescence

  • Cho, Sungdong
    • Journal of the Chosun Natural Science
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    • v.3 no.4
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    • pp.202-205
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    • 2010
  • Nanocrystalline porous silicon surfaces have been used to detect nitroaromatic compounds in vapor phase. The mode of photoluminescence is emphasized as a sensing attitude or detection technique. Quenching of photoluminescence from nanocrystalline porous surfaces as a transduction mode is measured upon the exposure of nitroaromatic compounds. Reversible detection mode for nitroaromatics is, too, observed. To verify the detection afore-mentioned, photoluminescent freshly prepared porous silicons are functionalized with different groups. The mechanism of quenching of photoluminescence is attributed to the electron transfer behaviors of quantum-sized nano-crystallites in the porous silicon matrix to the analytes(nitroaromatics). An attempt has been done to prove that the surface-derivatized photoluminescent porous silicone surfaces can act as versatile substrates for sensing behaviors due to having a large surface area and highly sensitive transduction mode.

Photoluminescence of Porous Silicon According to Various Etching Times and Various Applied Current Densities (식각시간 및 식각전류에 따른 다공성 실리콘의 발광 특성에 대한 조사)

  • Han, Jungmin
    • Journal of the Chosun Natural Science
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    • v.3 no.3
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    • pp.148-152
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    • 2010
  • Photoluminescence properties and surface morphologies of porous silicon etched with various applied current densities at fixed etching times. FE-SEM image of porous silicon surface indicated that the porous silicon prepared at currents below 200 mA exhibited very bright red photoluminescence properties. As the applied current densities increased, the photoluminescence efficiencies of porous silicon prepared at applied current densities above 300 mA decreased, and displayed the cracked surface on porous silicon. This cracked surface start to collapsed to give cracked domains.

PbS Quantum-dots in Glasses

  • Liu, Chao;Heo, Jong
    • Ceramist
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    • v.10 no.3
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    • pp.7-14
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    • 2007
  • PbS QDs in glasses have attracted much attention due to the potentials for near-infrared applications. Growth of PbS QDs in the glass is discussed and size of PbS QDs formed in the glass can be tuned by varying the thermal treatment conditions. Hyperbolic-band approximation and four-band envelope function provide good simulation of the exciton energies of PbS QDs. Absorption and photoluminescence of PbS QDs was tuned into $1{\sim}2{\mu}m$ wave-length regime with large full width at half maximum photoluminescence intensity (>160 nm). Photoluminescence intensity of PbS QDs in the glasses was closely related to size of quantum dots, temperature, excitation and defects. Decrease in temperature shifted the photoluminescence bands to shorter wavelength and switched the photoluminescence from darkened state and brightened state.

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Doping-Concentration and Annealing Effects on Photoluminescence Profile of Eu(III)-doped CeO2 nanorods

  • Lee, Juheon;Park, Yohan;Joo, Sang Woo;Sohn, Youngku
    • Bulletin of the Korean Chemical Society
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    • v.35 no.11
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    • pp.3319-3325
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    • 2014
  • Eu(III)-doped $CeO_2$ nanorods were prepared by a co-precipitation method at room temperature, and their photoluminescence profiles were examined with different Eu(III)-doping concentrations and thermal annealing temperatures. Scanning electron microscopy, X-ray diffraction crystallography and UV-Vis absorption spectroscopy were employed to examine the morphology, crystal structure and photon absorption profiles of the nanorods, respectively. Additionally, their 2D and 3D-photoluminescence profile maps were obtained to fully understand the photoluminescence mechanism. We found that the magnetic dipole $^5D_0{\rightarrow}^7F_1$ and the electric dipole $^5D_0{\rightarrow}^7F_2$ transitions of Eu(III) were highly dependent on the doping concentration, annealing temperature and excitation wavelength, which was explained by the presence of different Eu(III)-doping sites (with and without an inversion center) in the $CeO_2$ host with a cubic crystal structure.

Comparison of In-situ Er-doped GaN with Er-implanted GaN Using Photoluminescence and Photoluminescence Excitation Spectroscope (In situ Er 도핑된 GaN와 Er이 이온 주입된 GaN의 PL과 PLE 비교에 대한 연구)

  • 김현석;성만영;김상식
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.2
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    • pp.89-96
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    • 2003
  • Photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy have been performed at 6 K on the 1540 nm $^4$I$\_$(13/2)/\longrightarrow$^4$I$\_$(15/2)/ emission of Er$\^$+3/ in in situ Er-doped GaN The PL and PLE spectra of in situ Er-doped GaN are compared with those of Er-implanted GaN in this study. The lineshapes of the broad PLE absorption bands and the broad PL bands in the spectra of the in situ Er-doped GaN are similar to those in Er-doped glass rather than in the Er-implanted GaN. The PL spectra of this in situ Er-doped GaN are independent of excitation wavelength and their features are significantly different from the site-selective PL spectra of the Er-implanted GaN. These PL and PLE studies reveal that a single type of Er$\^$3+/ sites is present in the in situ Er-doped GaN and these Er sites are different from those observed in the Er-implanted GaN. In addition, the comparison of the PL single strength illustrates that the excitation of Er$\^$3+/ sites through the energy absorption of defects in Er-implanted GaN.

Investigation of Photoluminescence and Annealing Effect of PS Layers

  • Han, Chang-Suk;Park, Kyoung-Woo;Kim, Sang-Wook
    • Korean Journal of Materials Research
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    • v.28 no.2
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    • pp.124-128
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    • 2018
  • N-type porous silicon (PS) layers and thermally oxidized PS layers have been characterized by various measuring techniques such as photoluminescence (PL), Raman spectroscopy, IR, HRSEM and transmittance measurements. The top surface of PS layer shows a stronger photoluminescence peak than its bottom part, and this is ascribed to the difference in number of fine silicon particles of 2~3 nm in diameter. Observed characteristics of PL spectra are explained in terms of microstructures in the n-type PS layers. Common features for both p-type and n-type PS layers are as follows: the parts which can emit visible photoluminescence are not amorphous, but crystalline, and such parts are composed of nanocrystallites of several nm's whose orientations are slightly different from Si substrate, and such fine silicon particles absorb much hydrogen atoms near the surfaces. Light emission is strongly dependent on such fine silicon particles. Photoluminescence is due to charge carrier confinement in such three dimensional structure (sponge-like structure). Characteristics of visible light emission from n-type PS can be explained in terms of modification of band structure accompanied by bandgap widening and localized levels in bandstructure. It is also shown that hydrogen and oxygen atoms existing on residual silicon parts play an important role on emission stability.