0000000000034690

AUTHOR

Roman Dimitrov

showing 3 related works from this author

Photoluminescence of Ga-face AlGaN/GaN single heterostructures

2001

Abstract The radiative recombination in Ga-face Al 0.30 Ga 0.70 N/GaN single heterostructures (SHs) was studied by photoluminescence (PL) measurements. An energy shift of the excitonic transitions toward higher energies was observed, indicating the presence of residual compressive strain in the GaN layer. In addition to these exciton lines, a broad band energetically localized between the exciton lines and the LO-phonon replica was noticed in the undoped SH. From its energy position, excitation power dependence, as well as temperature behaviour, we have attributed this luminescence to the H -band (HB), which is representative of the two-dimensional electron gas (2DEG) recombination.

PhotoluminescenceMaterials scienceCondensed matter physicsCondensed Matter::OtherMechanical EngineeringExcitonHeterojunctionCondensed Matter::Mesoscopic Systems and Quantum Hall EffectCondensed Matter PhysicsCondensed Matter::Materials ScienceMechanics of MaterialsGeneral Materials ScienceSpontaneous emissionFermi gasLuminescenceExcitationRecombinationMaterials Science and Engineering: B
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Optical characterization of Mg-doped GaN films grown by metalorganic chemical vapor phase deposition

2000

Scanning electron microscopy, micro-Raman, and photoluminescence (PL) measurements are reported for Mg-doped GaN films grown on (0001) sapphire substrates by low-pressure metalorganic chemical vapor phase deposition. The surface morphology, structural, and optical properties of GaN samples with Mg concentrations ranging from 1019 to 1021 cm−3 have been studied. In the scanning micrographs large triangular pyramids are observed, probably due to stacking fault formation and three-dimensional growth. The density and size of these structures increase with the amount of magnesium incorporated in the samples. In the photoluminescence spectra, intense lines were found at 3.36 and 3.31 eV on the tr…

PhotoluminescenceMaterials scienceIII-V semiconductorsScanning electron microscopeAnalytical chemistryGeneral Physics and AstronomySemiconductor thin filmsChemical vapor depositionStacking faultsSurface topographysymbols.namesake:FÍSICA [UNESCO]MagnesiumGallium compounds ; III-V semiconductors ; Wide band gap semiconductors ; Magnesium ; Semiconductor thin films ; MOCVD coatings ; Scanning electron microscopy ; Raman spectra ; Photoluminescence ; Surface composition ; Surface topography ; Stacking faults ; Inclusions ; ExcitonsPhotoluminescenceWurtzite crystal structureDopingUNESCO::FÍSICAGallium compoundsWide band gap semiconductorsMOCVD coatingsSurface compositionInclusionssymbolsSapphireExcitonsRaman spectraRaman spectroscopyScanning electron microscopyStacking fault
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Residual strain effects on the two-dimensional electron gas concentration of AlGaN/GaN heterostructures

2001

Ga-face AlGaN/GaN heterostructures with different sheet carrier concentrations have been studied by photoluminescence and Raman spectroscopy. Compared to bulk GaN, an energy shift of the excitonic emission lines towards higher energies was observed, indicating the presence of residual compressive strain in the GaN layer. This strain was confirmed by the shift of the E2 Raman line, from which biaxial compressive stresses ranging between 0.34 and 1.7 GPa were deduced. The spontaneous and piezoelectric polarizations for each layer of the heterostructures have been also calculated. The analysis of these quantities clarified the influence of the residual stress on the sheet electron concentratio…

Electron densityTwo-dimensional electron gasMaterials sciencePhotoluminescenceIII-V semiconductorsAluminium compounds ; Gallium compounds ; III-V semiconductors ; Wide band gap semiconductors ; Semiconductor heterojunctions ; Two-dimensional electron gas ; Electron density ; Internal stresses ; Photoluminescence ; Raman spectra ; Excitons ; Interface states ; Piezoelectric semiconductors ; Dielectric polarisationExcitonAnalytical chemistryGeneral Physics and AstronomyDielectric polarisationMolecular physicsCondensed Matter::Materials Sciencesymbols.namesakeResidual stress:FÍSICA [UNESCO]Emission spectrumPiezoelectric semiconductorsPhotoluminescenceAluminium compoundsUNESCO::FÍSICAWide-bandgap semiconductorGallium compoundsHeterojunctionInterface statesWide band gap semiconductorssymbolsExcitonsRaman spectraSemiconductor heterojunctionsRaman spectroscopyInternal stressesElectron density
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