Quantum defect approach for the effect of electron–phonon coupling on impurity recombination in semiconductors

Gurskii, A. L.; Voitikov, S. V.

doi:10.1016/s0038-1098(99)00354-3

Cited by 25 publications

(31 citation statements)

References 18 publications

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“…We cannot do any accurate model because many physical parameters are lacking. But we can remember that the strength of coupling with LO-phonons for DAP is simply a growing function of the average distance R between donor and acceptor ions [41]. This is exactly what we have observed, a minimum for R being simply the distance between localization centers along the growth axis, i.e.…”

Section: Electric Field Versus Localizationsupporting

confidence: 74%

Carrier Dynamics in Group-III Nitride Low-Dimensional Systems: Localization versus Quantum-Confined Stark Effect

Lefèbvre

Taliercio

Kalliakos

et al. 2001

phys. stat. sol. (b)

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Continuous-wave and time-resolved optical spectroscopy is used to examine a variety of InGaN/GaN quantum-well and quantum-box samples, grown by molecular beam epitaxy. The results are analyzed in order to clarify the respective influences of electric fields and of carrier localizations on radiative recombinations. The coupling of electron-hole pairs with LO-phonons is also studied in detail, from careful analysis of the size-dependent intensities of LO-phonon replica. From our attempt of modelling the Huang-Rhys factor, S, for excitons in these systems, we conclude that the observed optical recombinations are rather those of electrons and holes separately localized on different potential fluctuations.Introduction All efficient light-emitting devices based on group-III nitride semiconductors involve low-dimensional systems, such as InGaN/GaN [1][2][3] or GaN/AlGaN [4] quantum wells (QWs). An intense research activity has been devoted recently to radiative recombinations in these artificial materials. For InGaN-based nanometric layers, large Stokes shifts have been readily assigned to strong carrier localization, possibly in self-formed quantum dots [5,6]. This idea was supported by observations of In-rich nanoclusters in InGaN layers. Although this clustering may depend on the growth conditions, the random distribution of In atoms induces rather strong potential fluctuations, in the volume of this ternary alloy. These fluctuations, together with large carrier effective masses in group-III nitrides, induce the localization of electron and hole wave-functions on nanometric scales, which prevents their efficient capture by nonradiative centers, related to the high density of threading dislocations. This localization was invoked to interpret (i) the strong Stokes shift between photoluminescence (PL) lines and the absorption onset of InGaN epilayers and QWs and (ii) the rather long PL decay times observed in these systems. Now, for all QWs based on nitrides in their wurtzite phase, including InGaN/GaN ones, electric fields of several hundred kV/cm are present, if the growth axis is (0001). Indeed, this symmetry permits spontaneous and piezoelectric polarizations which are specially strong for group-III nitrides [7,8]. These fields reduce drastically the oscillator strength for the ground-state optical transition, as evidenced [9, 10] by very large, sizedependent, recombination times. They are also partly at the origin of the Stokes shift observed in QWs [11].

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Section: Electric Field Versus Localizationsupporting

confidence: 74%

Carrier Dynamics in Group-III Nitride Low-Dimensional Systems: Localization versus Quantum-Confined Stark Effect

Lefèbvre

Taliercio

Kalliakos

et al. 2001

phys. stat. sol. (b)

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“…(1) and (3) that S generally depends strongly on the spatial separation of the electron and hole charge densities [3,17]. In the present case of nitride-based heterostructures, this spatial separation along the z-axis is enhanced by the internal electric field.…”

Section: Experimental and Theoretical Resultsmentioning

confidence: 79%

“…a growing function of the well width. In the case of real DAPs, this dependence can be calculated [17] by variational methods, provided that correct shapes of wave-functions are included. For the present system of potential fluctuations, too many physical parameters are unknown to justify any reliable choice for such trial functions.…”

Section: Experimental and Theoretical Resultsmentioning

confidence: 99%

The Effects of Localization and of Electric Fields on LO-Phonon-Exciton Coupling in InGaN/GaN Quantum Wells and Quantum Boxes

Kalliakos

Lefèbvre

Zhang

et al. 2002

phys. stat. sol. (a)

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The size dependence of the coupling between longitudinal optical phonons and electron-hole pairs in In x Ga 1--x N/GaN quantum wells and quantum boxes has been investigated. The distribution of luminescence intensities between the phonon replicas and the zero-phonon peak is found to depend significantly on the well width or the vertical size of the boxes. The Huang-Rhys factor, S, which describes the strength of the coupling between LO-phonons and electron-hole pairs, increases steadily with the vertical size. This behavior is assigned to 1. the spontaneous and piezoelectric polarization-induced strong electric field along the growth axis of the system and 2. to the localization of electrons and holes at opposite sides of the well (or box) resulting from potential fluctuations in the ternary alloy. This conclusion is reinforced by envelope function calculations of S, for free or localized excitons, where only the Coulomb interaction is responsible for the electron-hole distance. This model does not give any quantitative agreement with the experimental results which are rather similar to what is obtained for donor-acceptor pairs, with separate centers of localization for electrons and for holes.Introduction InGaN-based heterostructures have received a lot of attention lately due to their potential applications for efficient light emitting devices. This interest has been enhanced since the realization of blue, green and "amber" light emitting diodes and laser diodes, some of which are already commercially available [1]. However, this technological progress has not enlightened some of the intrinsic physical properties of these systems, such as the electron-phonon interaction, which plays a significant role in their optical and electronic properties.Various types of electron-phonon interactions can alter the optical properties of semiconductor heterostructures [2]. The Frö hlich interaction with longitudinal optical (LO) phonons is a Coulomb interaction between electrons and the longitudinal electric field produced by polar phonons. The deformation potential interaction with both optical and acoustic phonons is caused by the displacement of atoms from their equilibrium positions and affects the electronic band structure similarly to the effect of applying a strain. The piezoelectric interaction with acoustic phonons is possible in non-centrosymmetric crystals with an electric field produced by the strain through the piezoelectric effect. In luminescence spectra, an evidence of the electron-phonon interaction is the appearance of phonon replicas of free and impurity-bound excitons, or of donor-accep-

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“…This is consistent with the lower Huang-Rhys parameter for more closely spaced donoracceptor pairs. [48] Carbon is particularly problematic because it is the only impurity inherent in MOCVD growth of GaAs, arising as a decomposition product of TMG. [45] Other impurities such as Si and Zn can be eliminated using high purity precursor sources.…”

Section: Photoluminescencementioning

confidence: 99%

High Purity GaAs Nanowires Free of Planar Defects: Growth and Characterization

et al. 2008

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Quantum defect approach for the effect of electron–phonon coupling on impurity recombination in semiconductors

Cited by 25 publications

References 18 publications

Carrier Dynamics in Group-III Nitride Low-Dimensional Systems: Localization versus Quantum-Confined Stark Effect

Carrier Dynamics in Group-III Nitride Low-Dimensional Systems: Localization versus Quantum-Confined Stark Effect

The Effects of Localization and of Electric Fields on LO-Phonon-Exciton Coupling in InGaN/GaN Quantum Wells and Quantum Boxes

High Purity GaAs Nanowires Free of Planar Defects: Growth and Characterization

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