QUANTUM CONFINEMENT EFFECT IN HgTe NANOCRYSTALS AND VISIBLE LUMINESCENCE

Mercury Telluride ( HgTe ) nanocrystals with a mean size of 5.35 nm have been synthesized by an electrochemical technique. Structural analysis by transmission electron microscopy and glancing angle X-ray diffraction studies indicate the presence of cubic phase HgTe nanocrystals in the deposit. Optical absorption measurements reveal two well resolved excitonic peaks around 578.5 nm and 550 nm attributed to heavy hole valence band (HVB)–conduction band (CB) and light hole valence band (LVB)–CB transitions, respectively, and suggest a band opening of bulk inverted narrow band gap HgTe as a result of strong quantum confinement effect (QCE). Visible photoluminescence (PL) of HgTe nanocrystals indicates free exciton transition around 579.5 nm as observed from the PL measurement at 300 K along with a bound exciton dominated band around 588 nm. Micro-Raman measurements at 300 K indicate the 1LO vibrational mode at 142.6 cm-1 shifted by 6 cm-1 from its standard bulk value and confirm the QCE.

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CdS/Cyclohexylamine Inorganic–Organic Hybrid Semiconductor Nanofibers with Strong Quantum Confinement Effect

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2008.18345 ◽

2008 ◽

Vol 8 (8) ◽

pp. 3914-3920 ◽

Cited By ~ 1

Author(s):

Libo Fan ◽

Hongwei Song ◽

Haifeng Zhao ◽

Guohui Pan ◽

Lina Liu ◽

...

Keyword(s):

Quantum Confinement ◽

Quantum Confinement Effect ◽

Blue Shift ◽

Average Diameter ◽

Confinement Effect ◽

Dimethyl Formamide ◽

Organic Hybrid ◽

Cds Nanorods ◽

Transmission Electron ◽

20 Nm

Inorganic–organic hybrid semiconductor nanofibers of CdS/CHA (CHA = cyclohexylamine) were successfully synthesized by a simple solvothermal method. The fibers obtained had average diameter of 20 nm and length of several micrometers. In these fibers, periodic layer-like sub-nanometer structures with thickness of ∼3 nm were identified by high-resolution transmission electron microscope (HR-TEM). The absorption of the hybrids exhibited a large blue-shift in contrast to the bulk, which was attributed to strong quantum confinement effect (QCE) induced by internal sub-nanometer structures. Pure hexagonal wurtzite CdS (H-CdS) nanorods were also obtained by extracting the CdS/CHA hybrids with dimethyl formamide (DMF). The rods obtained had average diameter of 20 nm and length of 200 nm. A CdS/CHA/polyvinyl alcohol (PVA) composite film emitting white light was prepared by spin coating.

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Mercury-Telluride Nanocrystalline Thin Films: A Unique Photoluminescence in the Visible Regime

Journal of Metastable and Nanocrystalline Materials ◽

10.4028/www.scientific.net/jmnm.23.125 ◽

2005 ◽

Vol 23 ◽

pp. 125-128 ◽

Cited By ~ 3

Author(s):

S. Rath ◽

S.N. Sahu

Keyword(s):

Room Temperature ◽

Vibrational Mode ◽

Electrochemical Technique ◽

Cubic Phase ◽

Mercury Telluride ◽

Transmission Electron ◽

Absorption Studies ◽

Phase Range ◽

Foreign Impurities ◽

Nanocrystalline Thin Films

Stoichiometric mercury-telluride (HgTe) nanocrystals, free from any foreign impurities, have been prepared by an electrochemical technique. Transmission electron microscopy and selected area diffraction studies confirm that the size of HgTe nanocrystals with cubic phase range from 4 – 7 nm and are preferentially oriented. Optical absorption studies indicate that the band gap of HgTe nanocrystals is 2.14 eV. Room temperature photoluminescence measurements show band edge and trap dominated luminescence in the visible regime. Micro-Raman scattering analysis of the HgTe nanocrystals sample reveals the 1LO Raman vibrational mode is at 142.5 cm-1suggesting a shift of 6 cm-1 from it’s bulk value and confirms the crystalline size to be small.

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Comparative Analysis of ZnS:Mn2+ Nanophosphors Prepared by Hydrothermal and Low Temperature Precipitation Methods

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.128.53 ◽

2007 ◽

Vol 128 ◽

pp. 53-58 ◽

Cited By ~ 1

Author(s):

Je Hong Park ◽

Sung Hoon Lee ◽

Jong Su Kim ◽

Tae Wan Kim ◽

Hong Lee Park

Keyword(s):

Low Temperature ◽

Quantum Confinement ◽

Transition Probability ◽

Quantum Confinement Effect ◽

Confinement Effect ◽

Precipitation Method ◽

Cubic Phase ◽

Decay Times ◽

Hydrothermal Precipitation ◽

20 Nm

Manganese-doped ZnS nanophosphors were synthesized by two different methods: hydrothermal and low-temperature precipitation methods. The nanophosphors prepared by the hydrothermal precipitation and low-temperature methods had the size of 20 nm and 4 nm, respectively, and both were the cubic phase. The emission intensity of the nanophosphor prepared by the hydrothermal method was optimized at 10 mole % of Mn2+ concentration whereas that by low-temperature precipitation method was optimized at 3 mole % of Mn2+. The precipitationprepared nanophosphor, of size 4nm, showed a blueshift in the excitation spectrum and a redshift in the emission spectrum compared to the hydrothermal-prepared 20 nm nanophosphor. These phenomena can be explained in terms of the quantum confinement effect. The decay times especially were lengthened with decreasing particle size. This can be explained in terms of the variation in the transition probability induced from the quantum confinement effect.

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Opto-Electronic Properties of Green Synthesized ZnS Nanostructures

International Journal of Nanoscience ◽

10.1142/s0219581x17600328 ◽

2018 ◽

Vol 17 (04) ◽

pp. 1760032

Author(s):

Sujata Deb ◽

P. K. Kalita ◽

P. Datta

Keyword(s):

Quantum Confinement ◽

Quantum Confinement Effect ◽

Blue Shift ◽

Cubic Phase ◽

Capping Agent ◽

X Ray Diffraction ◽

Chemical Route ◽

Transmission Electron ◽

Wet Chemical ◽

Green Capping Agent

ZnS nanostructures are synthesized by a wet chemical route using starch as green capping agent under nitrogen environment. The as-prepared nanostructures are characterized structurally, optically and electrically. X-ray diffraction (XRD) spectra confirm that the zinc sulfide (ZnS) nanoparticles have cubic phase (zinc blende). UV–Vis spectrum of the sample clearly shows that the absorption peak exhibits blue shift compared to their bulk counterpart, which confirms the quantum confinement effect of the nanostructures. Its photoluminescence (PL) spectrum shows near band gap emission at 392[Formula: see text]nm and extrinsic emission at 467[Formula: see text]nm. The particle sizes calculated from XRD and UV studies are in fair agreement with high resolution transmission electron microscopy (HRTEM) results. Starch is found to be a noble capping agent in bringing quantum confinement. The synthesis under nitrogen environment has been observed to produce quality products by reducing the oxide traces. Moreover, the I–V characteristics under dark and illumination show that ZnS can be more suitable as photodetector.

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Synthesis and Characterization of Mn2+ Doped ZnS Using Reverse Miceller Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.970.283 ◽

2014 ◽

Vol 970 ◽

pp. 283-287

Author(s):

Rahizana Mohd Ibrahim ◽

Markom Masturah ◽

Huda Abdullah

Keyword(s):

Quantum Confinement ◽

Quantum Confinement Effect ◽

Blue Shift ◽

Band Gap Energy ◽

Confinement Effect ◽

X Ray Diffraction ◽

Transmission Electron ◽

Vis Spectroscopy ◽

Size Of Particles ◽

Absorbance Spectra

In this work we synthesized the monodisperse of Zn1-xMnxS with x =0.00,0.02,0.04,0.06,0.08 and 0.10 nanoparticles by reverse micelle method using sodium bis (2-ethylhexyl) sulfosuccinate (AOT) as surfactant. The prepared particles were characterized using UV-Visible Spectroscopy, X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Photoluminescence (PL) for size, morphology and optical of the samples .UV-vis absorbance spectra for all of the synthesized nanoparticles show the maximum absorption for all samples is observed at range 210 - 300 nm . The absorption edge shifted to lower wavelengths when doping with ion Mn as per UV-Vis spectroscopy. The band gap energy values were increase from 4.50eV to 4.90 eV. This blue shift is attributed to the quantum confinement effect. The size of particles is found to be 3-5nm range. The Mn2+ doped ZnS nanoparticles using reverse micelles method shows the enhance of PL intensity results in monodisperse nanoparticles. Keywords: Nanoparticles; UV-vis absorbance spectra; quantum confinement effect; photoluminescence.

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Tunable Quantum Confinement Effect on Non-volatile Thin Film Polymer Memory Device

10.1557/proc-1134-bb05-04 ◽

2008 ◽

Author(s):

Augustin J. Hong ◽

Kang L. Wang ◽

Wei Lek Kwan ◽

Yang Yang ◽

Dayanara Parra ◽

...

Keyword(s):

Thin Film ◽

Quantum Confinement ◽

Quantum Confinement Effect ◽

Memory Device ◽

Confinement Effect ◽

Film Polymer ◽

Polymer Memory

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Formation of Luminescent Si Nanocrystals by High-Temperature Annealing of Ion-Beam-Sputtered Si/SiO2 Multilayers

MRS Proceedings ◽

10.1557/proc-775-p9.57 ◽

2003 ◽

Vol 775 ◽

Author(s):

Suk-Ho Choi ◽

Jun Sung Bae ◽

Kyung Jung Kim ◽

Dae Won Moon

Keyword(s):

Quantum Confinement ◽

Radiative Recombination ◽

Ion Beam ◽

Quantum Confinement Effect ◽

Visible Range ◽

Ion Beam Sputtering ◽

Transmission Electron ◽

Si Nanocrystals ◽

Beam Sputtering ◽

Microscopy Images

AbstractSi/SiO2 multilayers (MLs) have been prepared under different deposition temperatures (TS) by ion beam sputtering. The annealing at 1200°C leads to the formation of Si nanocrystals in the Si layer of MLs. The high resolution transmission electron microscopy images clearly demonstrate the existence of Si nanocrystals, which exhibit photoluminescence (PL) in the visible range when TS is ≥ 300°C. This is attributed to well-separation of nanocrystals in the higher-TS samples, which is thought to be a major cause for reducing non-radiative recombination in the interface between Si nanocrystal and surface oxide. The visible PL spectra are enhanced in its intensity and are shifted to higher energy by increasing TS. These PL behaviours are consistent with the quantum confinement effect of Si nanocrystals.

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