Polar optical phonon states and their electron-phonon coupling properties in a wurtzite nitride quantum dot

2010 ◽  
Vol 74 (3) ◽  
pp. 397-407 ◽  
Author(s):  
L. Zhang ◽  
H. J. Xie ◽  
P. M. Shao
Keyword(s):  
Quantum Dot ◽  
Optical Phonon ◽  
Polar Optical Phonon ◽  
Phonon Coupling ◽  
Electron Phonon Coupling

VIBRATIONAL FREQUENCY OF IMPURITY BOUND MAGNETOPOLARON IN AN ANISOTROPIC QUANTUM DOT

2009 ◽  
Vol 23 (20n21) ◽  
pp. 2449-2456 ◽  
Author(s):  
WEI XIAO ◽  
JING-LIN XIAO
Keyword(s):  
Quantum Dot ◽  
Interaction Energy ◽  
Coupling Strength ◽  
Vibrational Frequency ◽  
Cyclotron Frequency ◽  
Operator Method ◽  
Phonon Coupling ◽  
Electron Phonon Coupling ◽  
Anisotropic Quantum Dot ◽  
Bound Magnetopolaron

We study the vibrational frequency and the interaction energy of the weak-coupling impurity bound magnetopolaron in an anisotropic quantum dot. The effects of the transverse and longitudinal effective confinement lengths, the electron–phonon coupling strength, the cyclotron frequency of a magnetic field and the Coulomb bound potential are taken into consideration by using an improved linear combination operator method. It is found that the vibrational frequency and the interaction energy will increase rapidly with decreasing confinement lengths and increasing the cyclotron frequency. The vibrational frequency is an increasing function of the Coulomb bound potential, whereas the interaction energy is an decreasing one of the potential and the electron–phonon coupling strength.

scholarly journals Ultra-broadband photodetectors based on epitaxial graphene quantum dots

Nanophotonics ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 735-740 ◽  
Author(s):  
Abdel El Fatimy ◽  
Anindya Nath ◽  
Byoung Don Kong ◽  
Anthony K. Boyd ◽  
Rachael L. Myers-Ward ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Quantum Confinement ◽  
Strong Dependence ◽  
Graphene Quantum Dots ◽  
Hot Electron ◽  
Phonon Coupling ◽  
Electron Phonon Coupling ◽  
Wide Range ◽  
Absorbed Power ◽  
Weak Electron

AbstractGraphene is an ideal material for hot-electron bolometers due to its low heat capacity and weak electron-phonon coupling. Nanostructuring graphene with quantum-dot constrictions yields detectors of electromagnetic radiation with extraordinarily high intrinsic responsivity, higher than 1×109 V W−1 at 3 K. The sensing mechanism is bolometric in nature: the quantum confinement gap causes a strong dependence of the electrical resistance on the electron temperature. Here, we show that this quantum confinement gap does not impose a limitation on the photon energy for light detection and these quantum-dot bolometers work in a very broad spectral range, from terahertz through telecom to ultraviolet radiation, with responsivity independent of wavelength. We also measure the power dependence of the response. Although the responsivity decreases with increasing power, it stays higher than 1×108 V W−1 in a wide range of absorbed power, from 1 pW to 0.4 nW.

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.

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