Quantum confinement effects and strain-induced band-gap energy shifts in core-shell Si-SiO2nanowires

2011 ◽  
Vol 83 (24) ◽  
Author(s):  
O. Demichel ◽  
V. Calvo ◽  
P. Noé ◽  
B. Salem ◽  
P.-F. Fazzini ◽  
...  
Keyword(s):  
Band Gap ◽  
Quantum Confinement ◽  
Band Gap Energy ◽  
Core Shell ◽  
Confinement Effects ◽  
Gap Energy ◽  
Quantum Confinement Effects

QUANTUM CONFINEMENT EFFECTS ON THE OPTICAL PROPERTIES OF ION BEAM SPUTTERED NICKEL OXIDE THIN FILMS

2001 ◽  
Vol 15 (02) ◽  
pp. 191-200 ◽  
Author(s):  
M. GHANASHYAM KRISHNA ◽  
A. K. BHATTACHARYA
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Nickel Oxide ◽  
Band Gap ◽  
Quantum Confinement ◽  
Ion Beam ◽  
Confinement Effects ◽  
Oxide Thin Films ◽  
Quantum Confinement Effects ◽  
Nickel Oxide Thin Films

Quantum confinement effects on the optical properties of ion beam sputtered nickel oxide thin films are reported. Thin films with crystallite sizes in the range 9 to 14 nm have been deposited on to fused silica substrates. There is an increase in band gap, from 3.4 to 3.9 eV, and a decrease in refractive index, from 2.4 to 1.6, with decrease in crystallite size, that can be attributed to quantum confinement effects. The effective mass approximation has been used to explain the observed behaviour in band gap variation.

scholarly journals Quantum-confinement effects in InAs–InP core–shell nanowires

2007 ◽  
Vol 19 (29) ◽  
pp. 295219 ◽  
Author(s):  
Z Zanolli ◽  
M-E Pistol ◽  
L E Fröberg ◽  
L Samuelson
Keyword(s):  
Quantum Confinement ◽  
Core Shell ◽  
Confinement Effects ◽  
Quantum Confinement Effects ◽  
Shell Nanowires

Band Gap Widening and Quantum Confinement Effects of ZnO Nanowires by First-Principles Calculation

2011 ◽  
Vol 675-677 ◽  
pp. 243-246 ◽  
Author(s):  
Mei Li Guo ◽  
Xiao Dong Zhang
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
First Principles ◽  
Quantum Confinement ◽  
Density Functional ◽  
High Energy ◽  
Zno Nanowires ◽  
First Principles Calculation ◽  
Confinement Effects ◽  
Quantum Confinement Effects

ZnO nanowires are promising for photonic devices, biosensor and cancer cell imaging. We have performed a first-principles study to evaluate the electronic and optical properties of ZnO nanowires. We have employed the Perdew–Burke–Ernzerhof form of generalized gradient approximation in the frame work of density functional theory. Calculations have been carried out at different configurations. With decreasing diameter, the band gap of ZnO nanowires is increased due to the increase of quantum confinement effects. The results of imaginary part of the dielectric function indicate that the optical transition between valence band and conduction band has shifted to the high energy range as the diameter decreases. The ZnO nanowires show size-tunable optical properties.

Band Gap Energy of Gradient Core–Shell Quantum Dots

2017 ◽  
Vol 121 (25) ◽  
pp. 13655-13659 ◽  
Author(s):  
Felipe Poulsen ◽  
Thorsten Hansen
Keyword(s):  
Quantum Dots ◽  
Band Gap ◽  
Band Gap Energy ◽  
Core Shell ◽  
Gap Energy

Quantum confinement effects and band gap engineering of SnO2 nanocrystals in a MgO matrix

2012 ◽  
Vol 60 (3) ◽  
pp. 1072-1078 ◽  
Author(s):  
M.B. Sahana ◽  
C. Sudakar ◽  
A. Dixit ◽  
J.S. Thakur ◽  
R. Naik ◽  
...  
Keyword(s):  
Band Gap ◽  
Quantum Confinement ◽  
Confinement Effects ◽  
Band Gap Engineering ◽  
Sno2 Nanocrystals ◽  
Quantum Confinement Effects

Quantum confinement effects in variable band-gap GaNxAs1−x thin films studied by photoacoustic spectroscopy

2003 ◽  
Vol 74 (1) ◽  
pp. 854-856 ◽  
Author(s):  
J. A. Cardona-Bedoya ◽  
A. Cruz-Orea ◽  
S. A. Tomas-Velazquez ◽  
O. Zelaya-Angel ◽  
J. G. Mendoza-Alvarez
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Photoacoustic Spectroscopy ◽  
Quantum Confinement ◽  
Confinement Effects ◽  
Quantum Confinement Effects ◽  
Variable Band Gap

Modification of optical properties of PC-PBT/Cr2O3 and PC-PBT/CdS nanocomposites by gamma irradiation

2020 ◽  
Vol 92 (2) ◽  
pp. 20402
Author(s):  
Kaoutar Benthami ◽  
Mai ME. Barakat ◽  
Samir A. Nouh
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Color Difference ◽  
Band Gap Energy ◽  
Polybutylene Terephthalate ◽  
Γ Irradiation ◽  
Gap Energy ◽  
Vis Spectroscopy ◽  
Oxygen Atoms

Nanocomposite (NCP) films of polycarbonate-polybutylene terephthalate (PC-PBT) blend as a host material to Cr2O3 and CdS nanoparticles (NPs) were fabricated by both thermolysis and casting techniques. Samples from the PC-PBT/Cr2O3 and PC-PBT/CdS NCPs were irradiated using different doses (20–110 kGy) of γ radiation. The induced modifications in the optical properties of the γ irradiated NCPs have been studied as a function of γ dose using UV Vis spectroscopy and CIE color difference method. Optical dielectric loss and Tauc's model were used to estimate the optical band gaps of the NCP films and to identify the types of electronic transition. The value of optical band gap energy of PC-PBT/Cr2O3 NCP was reduced from 3.23 to 3.06 upon γ irradiation up to 110 kGy, while it decreased from 4.26 to 4.14 eV for PC-PBT/CdS NCP, indicating the growth of disordered phase in both NCPs. This was accompanied by a rise in the refractive index for both the PC-PBT/Cr2O3 and PC-PBT/CdS NCP films, leading to an enhancement in their isotropic nature. The Cr2O3 NPs were found to be more effective in changing the band gap energy and refractive index due to the presence of excess oxygen atoms that help with the oxygen atoms of the carbonyl group in increasing the chance of covalent bonds formation between the NPs and the PC-PBT blend. Moreover, the color intensity, ΔE has been computed; results show that both the two synthesized NCPs have a response to color alteration by γ irradiation, but the PC-PBT/Cr2O3 has a more response since the values of ΔE achieved a significant color difference >5 which is an acceptable match in commercial reproduction on printing presses. According to the resulting enhancement in the optical characteristics of the developed NCPs, they can be a suitable candidate as activate materials in optoelectronic devices, or shielding sheets for solar cells.

Stability Investigation in the Optical Properties of Thermally Evaporated Ge5Se95-x Znx Thin Films

2015 ◽  
Vol 7 (3) ◽  
pp. 1923-1930
Author(s):  
Austine Amukayia Mulama ◽  
Julius Mwakondo Mwabora ◽  
Andrew Odhiambo Oduor ◽  
Cosmas Mulwa Muiva ◽  
Boniface Muthoka ◽  
...  
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Optical Band Gap ◽  
Thermal Evaporation ◽  
Optical Transition ◽  
Bulk Material ◽  
Band Gap Energy ◽  
Optical Absorbance ◽  
Gap Energy ◽  
Constituent Elements

 Selenium-based chalcogenides are useful in telecommunication devices like infrared optics and threshold switching devices. The investigated system of Ge5Se95-xZnx (0.0 ≤ x ≤ 4 at.%) has been prepared from high purity constituent elements. Thin films from the bulk material were deposited by vacuum thermal evaporation. Optical absorbance measurements have been performed on the as-deposited thin films using transmission spectra. The allowed optical transition was found to be indirect and the corresponding band gap energy determined. The variation of optical band gap energy with the average coordination number has also been investigated based on the chemical bonding between the constituents and the rigidity behaviour of the system’s network.

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