Search results for "Piezoelectric semiconductors"

showing 2 items of 2 documents

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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Modulation of the electronic properties of GaN films by surface acoustic waves

2003

We report on the interaction between photogenerated electron-hole pairs and surface acoustic waves (SAW) in GaN films grown on sapphire substrates. The spatial separation of photogenerated carriers by the piezoelectric field of the SAW is evidenced by the quenching of the photoluminescence (PL) intensity. The quenching levels in GaN are significantly smaller than those measured in GaAs under similar conditions. The latter is attributed to the lower exciton ionization efficiency and carrier separation probabilities mediated by the piezoelectric effect. The PL spectra also evidence energy shifts and broadenings of the electronic transitions, which are attributed to the band gap modulation by …

PhotoluminescenceMaterials scienceIII-V semiconductorsSurface acoustic wavesBand gapExcitonRadiation quenchingGeneral Physics and AstronomySemiconductor thin filmsCondensed Matter::Materials Science:FÍSICA [UNESCO]IonizationPiezoelectric semiconductorsPhotoluminescenceQuenchingbusiness.industryUNESCO::FÍSICAWide-bandgap semiconductorGallium compoundsAcoustic waveCondensed Matter::Mesoscopic Systems and Quantum Hall EffectWide band gap semiconductorsGallium compounds ; III-V semiconductors ; Wide band gap semiconductors ; Surface acoustic waves ; Semiconductor thin films ; Photoluminescence ; Radiation quenching ; Piezoelectric semiconductors ; Excitons ; Energy gapEnergy gapSapphireOptoelectronicsExcitonsbusiness
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