Effect of spectral overlap and mixing ratio on metal-semiconductor mixed colloid.

2021 ◽  
Author(s):  
Sabina Gurung ◽  
Asha Singh ◽  
J Jayabalan
Keyword(s):  
Optoelectronic Device ◽  
Semiconductor Quantum Dots ◽  
Advanced Materials ◽  
Mixing Ratio ◽  
Ag Nps ◽  
Time Resolved ◽  
Decay Component ◽  
Device Applications ◽  
Time Resolved Photoluminescence ◽  
Selection Of

Abstract Metal-semiconductor hybrid colloid is an emerging paradigm for construction of advanced materials having multiple functionalities. In such colloids, the ratio between the number of metal nanoparticles (NP) to the number of semiconductor quantum dots (QD) plays an important role in controlling the properties of the final hybrid colloid. We study the effect of mixing ratio of Ag NPs to the CdTe QDs on the photoluminscence (PL) properties of the final mixed hybrid colloid. Using steady-state and time-resolved photoluminescence, it has been shown that when exciton and plasmon spectrally overlap in a hybrid, the amplitude of the decay component of PL depends on the excitation energy. Such dependence is not observed in the case of hybrid where exciton and plasmon are spectrally separated. This study contributes to the appropriate selection of the shape of metal NPs in designing a hybrid material that is well suited for optoelectronic device applications.

scholarly journals Localized Surface Plasmon on 6H SiC with Ag Nanoparticles

2017 ◽  
Vol 897 ◽  
pp. 634-637
Author(s):  
Yi Wei ◽  
Ahmed Fadil ◽  
Hai Yan Ou
Keyword(s):  
Ag Nanoparticles ◽  
Internal Quantum Efficiency ◽  
Minority Carrier Lifetime ◽  
Fdtd Simulation ◽  
Localized Surface Plasmon ◽  
Ag Nanoparticle ◽  
Ag Nps ◽  
Time Resolved ◽  
Donor Acceptor ◽  
Time Resolved Photoluminescence

Silver (Ag) nanoparticles (NPs) were deposited on the surface of bulk Nitrogen-Boron co-doped 6H silicon carbide (SiC), and the Ag NPs were observed to induce localized surface plasmons (LSP) resonances on the SiC substrate, which was expected to improve the internal quantum efficiency (IQE) of the emissions of the donor-acceptor pairs of the SiC substrate. Room-temperature measurements of photoluminescence (PL), transmittance and time-resolved photoluminescence (TRPL) were applied to characterize the LSP resonances. Through the finite-difference time-domain (FDTD) simulation of the LSP resonance of an Ag nanoparticle on the SiC substrate, it is predicted that when the diameter of the cross section on the xy plane of the Ag nanoparticle is greater than 225 nm, the LSP starts to enhance the PL intensity. With implementation of a 3rd order exponential decay fitting model to the TRPL results, it is found that the average minority carrier lifetime of the SiC substrate decreased.

TEM and cathodoluminescence of precipitates in II-VI semiconductors

1988 ◽  
Vol 46 ◽  
pp. 488-489
Author(s):  
Joanna L. Batstone
Keyword(s):  
Crystal Growth ◽  
Band Gap ◽  
Local Strain ◽  
Wide Band ◽  
Optoelectronic Device ◽  
Wide Band Gap ◽  
Bulk Crystal Growth ◽  
Transmission Electron ◽  
Device Applications ◽  
Stoichiometry Control

Interest in II-VI semiconductors centres around optoelectronic device applications. The wide band gap II-VI semiconductors such as ZnS, ZnSe and ZnTe have been used in lasers and electroluminescent displays yielding room temperature blue luminescence. The narrow gap II-VI semiconductors such as CdTe and HgxCd1-x Te are currently used for infrared detectors, where the band gap can be varied continuously by changing the alloy composition x.Two major sources of precipitation can be identified in II-VI materials; (i) dopant introduction leading to local variations in concentration and subsequent precipitation and (ii) Te precipitation in ZnTe, CdTe and HgCdTe due to native point defects which arise from problems associated with stoichiometry control during crystal growth. Precipitation is observed in both bulk crystal growth and epitaxial growth and is frequently associated with segregation and precipitation at dislocations and grain boundaries. Precipitation has been observed using transmission electron microscopy (TEM) which is sensitive to local strain fields around inclusions.

Exciton dynamics in thick GaN MOVPE epilayers deposited on sapphire.

1997 ◽  
Vol 2 ◽  
Author(s):  
J. Allègre ◽  
P. Lefebvre ◽  
J. Camassel ◽  
B. Beaumont ◽  
Pierre Gibart
Keyword(s):  
Layer Thickness ◽  
Buffer Layers ◽  
Rate Equations ◽  
Time Resolved ◽  
Versus Layer ◽  
Level Model ◽  
Shallow Impurities ◽  
Aln Buffer ◽  
Time Resolved Photoluminescence

Time-resolved photoluminescence spectra have been recorded on three GaN epitaxial layers of thickness 2.5 μm, 7 μm and 16 μm, at various temperatures ranging from 8K to 300K. The layers were deposited by MOVPE on (0001) sapphire substrates with standard AlN buffer layers. To achieve good homogeneities, the growth was in-situ monitored by laser reflectometry. All GaN layers showed sharp excitonic peaks in cw PL and three excitonic contributions were seen by reflectivity. The recombination dynamics of excitons depends strongly upon the layer thickness. For the thinnest layer, exponential decays with τ ~ 35 ps have been measured for both XA and XB free excitons. For the thickest layer, the decay becomes biexponential with τ1 ~ 80 ps and τ2 ~ 250 ps. These values are preserved up to room temperature. By solving coupled rate equations in a four-level model, this evolution is interpreted in terms of the reduction of density of both shallow impurities and deep traps, versus layer thickness, roughly following a L−1 law.

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