Free exciton transitions and varshni's coefficients for GaN epitaxial layers grown by horizontal lp-mocvd

Viswanath, Annamraju Kasi; Lee, Joo In; Lee, C.R.; Leem, Jae Young; Kim, Dongho

doi:10.1016/s0038-1098(98)00378-0

Cited by 10 publications

(4 citation statements)

References 20 publications

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“…The peak emission energy is slightly different for the three spectra. This difference is related to the variation in the exciton density but may be contributed by the renormalization of the bandgap and the localisation effects at low temperature [19,30,31].…”

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Room-Temperature Transport of Indirect Excitons in(Al,Ga)N/GaNQuantum Wells

et al. 2016

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We report on the exciton propagation in polar (Al,Ga)N/GaN quantum wells over several micrometers and up to room temperature. The key ingredient to achieve this result is the crystalline quality of GaN quantum wells (QWs) grown on GaN template substrate. By comparing microphotoluminescence images of two identical QWs grown on sapphire and on GaN, we reveal the twofold role played by GaN substrate in the transport of excitons. First, the lower threading dislocation densities in such structures yield higher exciton radiative efficiency, thus limiting nonradiative losses of propagating excitons. Second, the absence of the dielectric mismatch between the substrate and the epilayer strongly limits the photon guiding effect in the plane of the structure, making exciton transport easier to distinguish from photon propagation. Our results pave the way towards room-temperature gate-controlled exciton transport in wide-bandgap polar heterostructures. PACS numbers:1 arXiv:1603.00191v1 [cond-mat.mes-hall]

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Room-Temperature Transport of Indirect Excitons in(Al,Ga)N/GaNQuantum Wells

et al. 2016

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“…18,19 Figure 1 shows the 9 K luminescence spectrum of a GaN epilayer on a c-face sapphire substrate. The spectrum has four unresolved and overlapping peaks.…”

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“…FX ͑A͒ and FX ͑B͒ are the free-exciton A and B transitions with respective energies at 3.481 and 3.489 eV with a peak separation of 8 meV, D 0 X is the neutral donor bound exciton with a peak at 3.475 eV, and D ϩ X at 3.469 eV is interpreted as being due to an ionized donor bound exciton transition. A detailed report on the optical properties of residual shallow donors will be published elsewhere, 18 in which the basis of assignment for the rarely observed ionized donor bound exciton is discussed. Free exciton A could be seen up to room temperature, while free exciton B was observed up to 150 K. The inset of Fig.…”

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Exciton-phonon interactions, exciton binding energy, and their importance in the realization of room-temperature semiconductor lasers based on GaN

et al. 1998

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Temperature dependence of the linewidths of free-exciton A and B transitions was investigated. Experimental linewidths were fitted to a theoretical model considering various interactions of excitons with phonons in addition to inhomogeneous broadening. It was shown that acoustic phonon scattering must also be considered to explain the emission linewidth broadening, in contrast to a recent report on luminescence linewidths in GaN. These exciton-acoustic-phonon interactions also explain the fast energy relaxation of free excitons to the bottom of the exciton band, which leads to generally observed short free-exciton lifetimes in GaN. The exciton-longitudinal-optical ͑LO͒ -phonon coupling constant was found to be extremely large. This was explained as being due to the Fröhlich interaction and the polar nature of GaN. The binding energy of both A and B excitons was found to be 26 meV. The relevance of exciton-phonon interactions and the binding energy of free excitons in achieving room-temperature exciton-based semiconductor lasers was discussed. Though exciton-LO-phonon interaction was very strong in GaN, it was still possible to observe room-temperature excitons since the exciton binding energy is very large.

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“…We have taken up a systematic investigation of GaN and other nitride semiconductors [3][4][5][6][7]. We have reported the very accurate bandgap of epitaxial GaN thin films, free exciton energies, exciton binding energies [3,4], energy levels of donors [5] and acceptors [6]. We also examined the exciton-phonon interactions and the conditions for room temperature lasing in this very important blue emitting material [7].…”

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confidence: 99%