Uniform description of polar optical phonon states and their Fröhlich electron–phonon interaction Hamiltonians in multi-layer wurtzite nitride low-dimensional quantum structures

Zhang, Li

doi:10.1016/j.spmi.2012.09.016

Cited by 21 publications

(4 citation statements)

References 71 publications

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“…4(b). To a certain extent, this picture is similar to the common concept of phonon confinement in nanostructures [96,101,102] that leads, e.g., to a backfolding of phonon branches. Consequently, a gradual increase in the localization of the phonon modes should indeed lead to the observed decrease in the phonon energy (E 1 opt ) and to an enhanced exciton-phonon coupling strength (γ 1 opt ), which scales with the overlap between the exciton wave function and the particular phonon mode of interest [96].…”

Section: B Analysis Of the Local Indium Distribution Around Impuritysupporting

confidence: 53%

Probing Alloy Formation Using Different Excitonic Species: The Particular Case of InGaN

2019

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Since the early 1960s, alloys are commonly grouped into two classes that feature either bound states in the band gap (I) or additional, nondiscrete band states (II). Consequently, one can observe either excitons bound to isoelectronic impurities or the typical band edge emission of a semiconductor that shifts and broadens with rising isoelectronic doping concentration. Microscopic parameters for class I alloys can directly be extracted from photoluminescence (PL) spectra, whereas any conclusions drawn for class II alloys usually remain limited to macroscopic assertions. Nonetheless, we present a spectroscopic study on exciton localization in a mixed-crystal alloy (class II) that allows us to access microscopic alloy parameters. In order to illustrate our approach, we study bulk In x Ga 1−x N epilayers at the onset of alloying (0 ≤ x ≤ 2.4%) in order to understand their robustness to point and structural defects. Through an indepth PL analysis it is demonstrated how different excitonic complexes (free, bound, and complex bound excitons) can serve as a probe to monitor the dilute limit of class II alloys. From an x-dependent linewidth analysis we extract the length scales at which excitons become increasingly localized, i.e., their conversion from a free to a bound particle upon alloy formation. Already at x ¼ 2.4% the exciton diffusion length is reduced to 5.7 AE 1.3 nm at a temperature of 12 K; hence, detrimental exciton transfer mechanisms toward nonradiative defects are suppressed. In addition, the associated low-temperature PL data suggest that a single indium atom cannot permanently capture an exciton. The low density of silicon impurities in our samples even allows studying their local indium-enriched environment at the scale of the exciton Bohr radius based on impurity bound excitons. The associated temperature-dependent PL data reveal an alloying dependence for the exciton-phonon coupling. Thus, the formation of the random alloy can not only be monitored by the emission of various excitonic complexes, but also more indirectly via the associated coupling(s) to the phonon bath. Micro-PL spectra even give access to a probing of silicon bound excitons embedded in a particular environment of indium atoms thanks to the emergence of a series of individual and energetically sharp emission lines (full width at half maximum ≈300 μeV). Consequently, the present study allows us to extract microscopic properties formerly mostly only accessible for class I alloys.

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Section: B Analysis Of the Local Indium Distribution Around Impuritysupporting

confidence: 53%

Probing Alloy Formation Using Different Excitonic Species: The Particular Case of InGaN

2019

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“…This is obviously different from the situations of GaN/AlGaN heterostructures because both sides of the heterostructure are polar semiconductor materials. [ 15,36,37 ]…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

Dispersive Spectra of Phonon Modes and Fröhlich Electron–Phonon Coupling Properties in AlGaN Quantum Rings: Wurzite versus Zinc‐Blende Structure

Zhang

Shao

Pang³

2022

Physica Status Solidi (b)

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The influence of crystal structure on the phonon modes and electron–phonon coupling properties in nitride quantum ring (QR) structures is investigated based on the macroscopic dielectric continuum model. It is found that three types of phonon modes including the surface optical (SO) phonon modes, the exact confined (EC) modes, and quasiconfined (QC) modes can coexist in the wurtzite nitride QR. However, only the SO modes and EC modes may appear in zinc‐blende nitride QR, and the QC modes cannot exist in zinc‐blende QRs in general. Numerical calculation on AlN QR shows that the SO modes of zinc‐blende QR are more dispersive than those of wurtzite QR. Furthermore, the degenerative behavior of QC modes to SO modes in wurtzite QRs is clearly observed. Moreover, the electron–phonon coupling functions in zinc‐blende QRs are larger than those in wurtzite QRs. These results reveal that the crystal structures greatly affect not only the type of phonon mode, but also the coupling strength of electron–phonon interaction. The present theoretical scheme and the numerical results are quite useful and important for further understanding and investigating the polaronic effect and related physical properties in wurtzite and zinc‐blende nitride QRs.

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“…and e z are the frequency-dependent dielectric functions parallel and perpendicular to z directions. They are given as 37 …”

Section: Theorymentioning

confidence: 99%

Interface optical phonon modes in wurtzite quantum heterostructures

Zhang

Liao

Dutta

et al. 2013

Journal of Applied Physics

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Surface and interface phonon polariton characteristics of wurtzite ZnO/GaN heterostructure Appl. Phys. Lett. 98, 241909 (2011); 10.1063/1.3599715The lifetime of optical phonons in a single heterostructure Simple analytical expressions are derived, herein, for the interface phonon modes of complex SiCand GaN-based substrates. These analytical results are essential for studies of remote polar-optical phonon phenomena in a variety of structures including heterostructures, in two-dimensional (2D) structures such and graphene, BN, and MoS 2 on polar substrates, as well as in efforts to control the bandgaps of such 2D structures through interactions with polar substrates. V C 2013 AIP Publishing LLC.

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Uniform description of polar optical phonon states and their Fröhlich electron–phonon interaction Hamiltonians in multi-layer wurtzite nitride low-dimensional quantum structures

Cited by 21 publications

References 71 publications

Probing Alloy Formation Using Different Excitonic Species: The Particular Case of InGaN

Probing Alloy Formation Using Different Excitonic Species: The Particular Case of InGaN

Dispersive Spectra of Phonon Modes and Fröhlich Electron–Phonon Coupling Properties in AlGaN Quantum Rings: Wurzite versus Zinc‐Blende Structure

Interface optical phonon modes in wurtzite quantum heterostructures

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