Phonon states of polar mixing optical modes in wurtzite ZnO-based coupling quantum dots

Zhang, Li; Shi, Junjie

doi:10.1016/j.ssc.2013.09.036

Cited by 3 publications

(1 citation statement)

References 24 publications

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“…ZnO, a II-IV semiconductor which is one of the favourable candidates among metal oxides in nanoelectronic science, has a wide bandgap of 3.37 eV at room temperature, high exciton binding energy (60 meV), and perfect stability under ambient conditions [1][2][3]. Due to its unique and fascinating structural, thermal, optical, electronic, and magnetic properties, different particle sizes of ZnO have been widely fabricated for transistors, light-emitting devices, solar cells, piezoelectric devices, photocatalysts, photovoltaic, gas sensors, and field-emission devices as well as chemical and biological sensors [4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

A Simple Up-Scalable Thermal Treatment Method for Synthesis of ZnO Nanoparticles

Lee

Saion

Al‐Hada

et al. 2015

Metals

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Abstract:A simple thermal treatment method, utilizing only zinc nitrate, polyvinyl pyrrolidone (PVP), and deionized water, was used to synthesize ZnO nanoparticles, and their characteristics were investigated by various techniques. The TGA measurement demonstrated that the bulk of the capping agent PVP can be removed at temperatures higher than 500 °C and is consistent with the absence of the majority of PVP absorption peaks in the FT-IR spectra. The formation of almost pure ZnO nanoparticles was established by the presence of single absorption peak in the FT-IR spectra due to being only Zn-O bonds at calcination temperatures of 500 °C and above. The TEM images revealed that the nanoparticles have a spherical shape and the particle size increased from 60.1-83.1 nm with an increase in calcination temperatures from 500-600 °C. The XRD diffraction patterns indicated that the particles are of a wurzite lattice structure. The optical properties were determined by UV-Vis spectrophotometer, and it was found that the band gap of ZnO nanoparticles decreased from 3.249-3.239 eV with an increase in calcination temperature from 500-600 °C.

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Section: Introductionmentioning

confidence: 99%

A Simple Up-Scalable Thermal Treatment Method for Synthesis of ZnO Nanoparticles

Lee

Saion

Al‐Hada

et al. 2015

Metals

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

Zhang

Shi

2014

Int. J. Mod. Phys. B

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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 Mg x Zn 1-x O crystal, the dielectric functions of Mg x Zn 1-x O 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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Potential distribution of polar optical phonons and their electron–phonon coupling properties of a wurtizite GaN-based trianglar quantum dot

Zhang

2022

Int. J. Mod. Phys. B

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Polar optical phonon modes of a wurtzite nitride trianglar quantum dot (QD) are deduced and analyzed by using the dielectric continuum model. Based on a method of nonseparable variables, the Laplace equation of electristatic potential of the structure is solved, and the exact and analytical phonon states of exact confined (EC) modes are derived. It is found that the frequency of EC modes in the nitride trianglar QD systems can take both the longitudinal optical phonons in [Formula: see text]-direction [Formula: see text] and the longitudinal optical phonons in [Formula: see text]-plane [Formula: see text], which is obviously different from the cases of EC modes in wurtzite GaN quantum wells and quantum wires due to their different confined dimensions. The polarization eigenvectors and their orthogonality relations for the EC phonon modes are derived, which could form a set of orthogonal and completed basis vectors. By using the orthogonality relations of polarization eigenvector and field quantization method, the free phonon field of EC modes and the corresponding Fröhlich electron–phonon interaction Hamiltonian are obtained. Numerical calculations on a wurtztie GaN trianglar QD are performed. The spatial distributions of phonon potentials of EC phonons both in [Formula: see text]-plane and in [Formula: see text]-direction as well as the electron–phonon coupling strength are plotted and discussed. It is observed that the potential of these EC phonon modes is strictly confined within the trianglar QD ranges. The dependence of symmetries and electron–phonon coupling strength on the quantum numbers [Formula: see text] and [Formula: see text] in [Formula: see text]-plane, and the quantum number [Formula: see text] in [Formula: see text]-direction are analyzed in detail. The relationship of the total number of peaks and troughs with these quantum numbers are also discussed and induced.

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Phonon states of polar mixing optical modes in wurtzite ZnO-based coupling quantum dots

Cited by 3 publications

References 24 publications

A Simple Up-Scalable Thermal Treatment Method for Synthesis of ZnO Nanoparticles

A Simple Up-Scalable Thermal Treatment Method for Synthesis of ZnO Nanoparticles

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

Potential distribution of polar optical phonons and their electron–phonon coupling properties of a wurtizite GaN-based trianglar quantum dot

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