Quantum size and dielectric effects of polar optical phonon spectra in wurtzite nitride quantum dots

2010 ◽  
Vol 247 (2) ◽  
pp. 375-384 ◽  
Author(s):  
L. Zhang
Keyword(s):  
Quantum Dots ◽  
Optical Phonon ◽  
Polar Optical Phonon ◽  
Quantum Size ◽  
Phonon Spectra

Polar optical phonon states and their degenerative behaviors of wurtziteZnO/MgZnOcoupling quantum dots

2014 ◽  
Vol 28 (11) ◽  
pp. 1430005 ◽  
Author(s):  
Li Zhang ◽  
J. J. Shi
Keyword(s):  
Quantum Dots ◽  
Optical Phonon ◽  
Quantum Systems ◽  
Quantum Structures ◽  
Polar Optical Phonon ◽  
Confined Systems ◽  
Phonon Modes ◽  
Electron Phonon Coupling ◽  
Low Dimensional ◽  
Theoretical Results

Analytical polar optical phonon states in a wurtzite ZnO -based cylindrical coupling quantum dots (CQDs) with arbitrary number of quantum dots (QDs) are deduced and analyzed. It is found that there are four types of polar mixing optical phonon modes, i.e., the z-IO/ρ-QC modes, the z-PR/ρ-IO modes, the z-QC/ρ-QC modes and the z-HS/ρ-IO modes coexisting in the ZnO -based CQDs. Within the framework of the macroscopic dielectric continuum model, the dispersive equations are derived by using the transferring matrix method. And the Fröhlich electron–phonon interaction Hamiltonians are obtained via a standard procedure of field quantization. The relationships between the present ZnO -based CQDs and the ZnO -based quantum wells (QWs) or the nanowires (NWs) are analyzed, and the general features of phonon modes in ZnO -based low-dimensional quantum structures are concluded and discussed. Under certain conditions, the present theoretical results in wurtzite ZnO -based CQDs can be naturally degenerate into those in wurtzite ZnO -based single or double QDs, wurtzite NWs and QWs and even into cubic quantum confined structures. This just embodies the intrinsic consistency of phonon mode theories in low-dimensional confined systems with different confined dimensions. Due to the ternary mixing effect of MgxZn1-xO crystal, the dielectric functions of MgxZn1-xO crystals are quite complicated, and the phonon modes in ZnO -based quantum structures have both the features of phonon modes in anisotropic wurtzite confined systems and isotropic rock-salt crystal quantum systems. The characteristics of electron–phonon coupling strength in ZnO -based quantum systems are summarized. Very strong polaronic effect could be prognosticated and anticipated in ZnO -based low-dimensional quantum structures because of their quite large electron–phonon coupling constants. The theoretical results and conclusions described in this paper also can be looked on as a summary of phonon states and their general features in ZnO -based quantum confined systems.

Effect of phonon confinement on one- and two-polar optical phonon capture processes in quantum dots

2015 ◽  
Vol 66 ◽  
pp. 268-274 ◽  
Author(s):  
K.A. Vardanyan ◽  
A.L. Vartanian ◽  
V.N. Mughnetsyan ◽  
A.V. Dvurechenskii ◽  
A.A. Kirakosyan
Keyword(s):  
Quantum Dots ◽  
Optical Phonon ◽  
Polar Optical Phonon ◽  
Phonon Confinement

Polar Optical Phonon Instability and Intervalley Transfer in Gallium Nitride

1998 ◽  
Vol 512 ◽  
Author(s):  
B. E. Foutz ◽  
S. K. O'leary ◽  
M. S. Shur ◽  
L. F. Eastman ◽  
B. L. Gelmont ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Analytical Model ◽  
Optical Phonon ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Polar Optical Phonon ◽  
Scattering Mechanism ◽  
Loss Mechanism ◽  
One Dimensional ◽  
Optical Phonon Scattering

ABSTRACTWe develop a simple, one-dimensional, analytical model, which describes electron transport in gallium nitride. We focus on the polar optical phonon scattering mechanism, as this is the dominant energy loss mechanism at room temperature. Equating the power gained from the field with that lost through scattering, we demonstrate that beyond a critical electric field, 114 kV/cm at T = 300 K, the power gained from the field exceeds that lost due to polar optical phonon scattering. This polar optical phonon instability leads to a dramatic increase in the electron energy, this being responsible for the onset of intervalley transitions. The predictions of our analytical model are compared with those of Monte Carlo simulations, and are found to be in satisfactory agreement.

The Emission Property of Phosphors LEDs Based on ZnCuInS/ZnSe/ZnS Quantum Dots

2014 ◽  
Vol 989-994 ◽  
pp. 623-625
Author(s):  
Ke Bi ◽  
Wen Yan Liu ◽  
Tian Yue Xu ◽  
Tie Qiang Zhang ◽  
Yu Zhang
Keyword(s):  
Quantum Dots ◽  
Photoluminescence Spectrum ◽  
Stokes Shift ◽  
Core Shell ◽  
Photoluminescence Properties ◽  
Red Emission ◽  
Light Emitting ◽  
Quantum Size ◽  
Gan Led ◽  
Photoluminescence Peak

.In this research, ZnCuInS/ZnSe/ZnS quantum dots (QDs) have been studied as an excellent red emitting source for blue GaN LED because of its non-toxic deep red emmission, and large Stokes shift properties. In the paper ZnCuInS/ZnSe/ZnS core/shell quantum dots were prepared with the particle size of 4.5nm. According to the measurement of photoluminescence spectrum emitted by ZnCuInS/ZnSe/ZnS core/shell quantum dots, the emitting peak of 700 nm and the full was achieved as red emitter.It was found that absorption edge and photoluminescence peak shifted to shorter wavelength with decreasing the nanocrystal size due to quantum size effect.Meanwhile, we were prepared ZnCuInS/ZnSe/ZnS core/shell quantum dot light emitting diodes and their photoluminescence properties were studied. After the suitable bias was applied on the films, increasing the ZnCuInS/ZnSe/ZnS QDs concentration in the blue GaN chips, red emission increased with decreasing LED’s blue light.

Applications of Quantum Dots in Cancer Research

2011 ◽  
Vol 345 ◽  
pp. 29-34
Author(s):  
Xue Feng Wang ◽  
Jing Ding ◽  
Ji Yu Li ◽  
Han Jiang ◽  
Zi Hao Wang ◽  
...  
Keyword(s):  
Cancer Research ◽  
Quantum Dots ◽  
Optical Properties ◽  
Nanocrystalline Materials ◽  
Mammary Cancer ◽  
Cell Tracking ◽  
Bohr Radius ◽  
Quantum Size ◽  
Highly Sensitive ◽  
Diagnosis Rate

Quantum dots(QDs) usually refers to nanocrystalline materials whose diameter is smaller than the exciton Bohr radius. These materials have quantum size effect,the most significant manifestation is their optical properties change with particle size.The unique optical properties make quantum dots to be Ideal markers for tumor cell tracking and targeting,such as mammary cancer, liver cancer, and melanoma.There are broad prospects in tapping the potential of this highly sensitive technology in serum and other body fluids, so as to increase the early diagnosis rate of tumors.

Homogeneous broadening of the zero-optical-phonon spectral line in semiconductor quantum dots

2001 ◽  
Vol 12 (4) ◽  
pp. 518-522 ◽  
Author(s):  
S V Goupalov ◽  
R A Suris ◽  
P Lavallard ◽  
D S Citrin
Keyword(s):  
Quantum Dots ◽  
Spectral Line ◽  
Optical Phonon ◽  
Semiconductor Quantum Dots ◽  
Homogeneous Broadening
Sign in / Sign up

Export Citation Format

Share Document