Absorption, Reflectance, and Luminescence of GaN Epitaxial Layers

Dingle, R.; Sell, D. D.; Stokowski, S. E.; Ilegems, M.

doi:10.1103/physrevb.4.1211

Cited by 536 publications

(225 citation statements)

References 18 publications

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“…Indeed, dominant resonance structures due to A and B FEs were found in both absorption and photoreflectance spectra of 3D GaN layers, and FE emission has been found even at RT, 39,40 since the exciton binding energy, E b , is as large as 26 meV and a B is as small as 3.4 nm. 20,[39][40][41][42][43] It is also known that E b is increased in QWs 44 due to confinement of wavefunctions.…”

Section: Frameworkmentioning

confidence: 99%

Spectroscopic Studies in InGaN Quantum Wells

Chichibu

Sota

Wada

et al. 1999

MRS Internet j. nitride semicond. res.

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Cite this article as: MRS Internet J. Nitride Semicond. Res. 4S1, G2.7(1999). AbstractFundamental electronic modulations in strained wurtzite III-nitride, in particular In x Ga 1-x N, quantum wells (QWs) were treated to explore the reason why practical InGaN devices emit bright luminescences in spite of the large threading dislocation (TD) density. The emission mechanisms were shown to vary depending on the well thickness L and InN molar fraction x. The electric field across the QW plane, F, which is a sum of the fields due to spontaneous and piezoelectric polarization and the pn junction field, causes the redshift of the ground state resonance energy through the quantum confined Stark effect (QCSE). The absorption spectrum is modulated by QCSE, quantum-confined Franz-Keldysh effect (QCFK), and Franz-Keldysh (FK) effect from the barrires when, for the first approximation, potential drop across the well (F L) exceeds the valence band discontinuity, E V . Under large F L, holes are confined in the triangular potential well formed at one side of the well. This produces apparent Stokes-like shift in addition to the in-plane net Stokes shift on the absorption spectrum. The QCFK and FK further modulate the electronic structure of the wells with L greater than the three dimensional (3D) free exciton (FE) Bohr radius, a B . When F L exceeds E C , both electron (e) and hole (h) confined levels drop into the triangular potential wells at opposite sides of the wells, which reduces the wavefunction overlap. Doping of Si in the barriers partially screens the F resulting in a smaller Stokes-like shift, shorter recombination decay time, and higher emission efficiency. Finally, the use of InGaN was found to overcome the field-induced oscillator strength lowering due to the spontaneous and piezoelectric polarization. Effective in-plane localization of the QW excitons (confined excitons, or quantized excitons) in quantum disk (Q-disk) size potential minima, which are produced by nonrandom alloy potential fluctuation enhanced by the large bowing parameter and F, produces confined e-h pairs whose wavefunctions are still overlapped when L

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Section: Frameworkmentioning

confidence: 99%

Spectroscopic Studies in InGaN Quantum Wells

Chichibu

Sota

Wada

et al. 1999

MRS Internet j. nitride semicond. res.

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“…In the symmetry-inappropriate context of a band to band description of the optical transitions at the band-gap energy of the wurtzite semiconductors ͑e.g., GaN͒, they, respectively, correspond to the commonly discussed A, B, and C transitions. 11,12 The two-component nature of the ⌫ 7 wave functions indicates that the band to band transitions are allowed in both ͑E Ќ c͒ and ͑E ʈ c͒ polarizations with relative oscillator strength being proportional to the square of their expansion components along ͉1͘, ͉1͘, and ͉0͘ spinless valence-band states. 13 Including the two components of the spin, the valenceband states are sometimes expressed in the basis set of spherical angular momenta.…”

Section: ͑10͒mentioning

confidence: 99%

Internal structure of acceptor-bound excitons in wide-band-gap wurtzite semiconductors

et al. 2010

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We describe the internal structure of acceptor-bound excitons in wurtzite semiconductors. Our approach consists in first constructing, in the context of angular momentum algebra, the wave functions of the two-hole system that fulfill Pauli's exclusion's principle. Second, we construct the acceptor-bound exciton states by adding the electron states in a similar manner that two-hole states are constructed. We discuss the optical selection rules for the acceptor-bound exciton recombination. Finally, we compare our theory with experimental data for CdS and GaN. In the specific case of CdS for which much experimental information is available, we demonstrate that, compared with cubic semiconductors, the sign of the short-range hole-exchange interaction is reversed and more than one order of magnitude larger. The whole set of data is interpreted in the context of a large value of the short-range hole-exchange interaction ⌶ 0 = 3.4Ϯ 0.2 meV. This value dictates the splitting between the ground-state line I 1 and the other transitions. The values we find for the electron-hole spin-exchange interaction and of the crystal-field splitting of the two-hole state are, respectively, −0.4Ϯ 0.1 and 0.2Ϯ 0.1 meV. In the case of GaN, the experimental data for the acceptor-bound excitons in the case of Mg and Zn acceptors, show more than one bound-exciton line. We discuss a possible assignment of these states.

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“…Research over recent years has led to room temperature blue-violet laser emission in group III nitride quantum well structures for both pulsed 1,2 and continuous wave operation. 3 The development of devices based on these materials has resulted in a demand for their characterization, and experimental and theoretical studies have established reliable values for such quantities as lattice parameters [4][5][6] and fundamental band gaps, [7][8][9] but many other parameters remain uncertain. For device modeling, calculations on optical gain have been performed on both bulk and quantum well structures.…”

Section: Introductionmentioning

confidence: 99%

Direct calculation ofk⋅pparameters for wurtzite AlN, GaN, and InN

2000

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Electronic band structure calculations have been performed for the wurtzite structures of AlN, GaN, and InN. In particular, the conventional k•p valence band parameters A i (iϭ1 -7) have been computed from initial empirical pseudopotential calculations in two distinct ways. A Monte Carlo fitting of the k•p band structure to the pseudopotential data was used to produce one set. Another set was obtained directly from the formulas for the A i in terms of the momentum matrix elements and energy eigenvalues at the center of the Brillouin zone. Both methods of calculating the k•p parameters produce band structures in excellent agreement with the original empirical band calculations near the center of the Brillouin zone. The advantage of the direct method is that it produces a unique set of k•p parameters, in contrast to a fitting procedure in which a range of equally valid parameter sets can exist.

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Absorption, Reflectance, and Luminescence of GaN Epitaxial Layers

Cited by 536 publications

References 18 publications

Spectroscopic Studies in InGaN Quantum Wells

Spectroscopic Studies in InGaN Quantum Wells

Internal structure of acceptor-bound excitons in wide-band-gap wurtzite semiconductors

Direct calculation ofk⋅pparameters for wurtzite AlN, GaN, and InN

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