0000000000034692
AUTHOR
G. Martı́nez-criado
showing 6 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.
Excitonic Transitions in Homoepitaxial GaN
2001
The photoluminescence spectrum of a high quality homoepitaxial GaN film has been measured as a function of temperature. As temperature increases the recombination of free excitons dominates the spectra. Their energy shift has successfully fitted in that temperature range by means of the Bose-Einstein expression instead of Varshni's relationship. Values for the parameters of both semi-empirical relations describing the energy shift are reported and compared with the literature.
The effect of reducing dimensionality on the excitonic recombination in InAs/InP heterostructures
1997
In this work we study the exciton recombination of InAs/InP self-organized quantum dots by means of photolumincscence (PL) as a function of temperature and excitation density. Well defined islands, spatially separated in most cases, and with different size distribution, make localized exciton recombination the dominant contribution to the PL spectrum. From our experimental results, we propose the co-existence of two types of islands, one with small height whose contribution to the PL spectra is important in samples with low InAs coverage (below two monolayers), and the properly 3D islands, whose dimensions and sheet concentration increase with the InAs coverage. Good quality structures are …
Two‐Dimensional Electron Gas Effects on the Photoluminescence from a Nonintentionally Doped AlGaN/GaN Heterojunction
2002
Photoluminescence measurements on an AlGaN/GaN single heterojunction (SH), where piezoelectric and spontaneous polarization effects confine a two-dimensional electron gas (2DEG), are presented. Well-defined emissions between the bulk excitonic transitions and their LO-phonon replica are attributed to spatially indirect excitons located close to the interface. The strong interfacial electric field separates photogenerated holes and electrons, weakening their Coulomb interaction and causing a blueshift with increasing excitation intensity due to carrier population effects. In addition, direct experimental proof is obtained by applying an electric field normal to the interface. An energy shift…
Study of inversion domain pyramids formed during the GaN:Mg growth
2003
AbstractThestudyofstructuraldefectsinducedbytheintroductionofMgduringthegrowthofMOCVDGaNispresented.Themagnesiumincorporationintothecrystalgrowthnotonlyinduceschangesinthestackingsequencefromhex-agonaltocubicstructures,butalsoinvertstheGaNpolarityfromGa-facetoN-face.Basedonthedifferentsurfacestructureandsurfacemigrationlengthofabsorbingprecursorsforeachpolaritytype(Ga-orN-face),the3DgrowthontopoftheN-facetriangulardefectisdescribed.TheN-facematerialischaracterizedbythreedanglingbondsofni-trogenthatpointuptowardthec-planesurface,enhancingthecrystalgrowthalongthec-axis. 2002ElsevierScienceLtd.Allrightsreserved. Keywords:Inversiondomain;Stackingfault;Polarity 1. IntroductionFurther progress tow…
Optical study of gallium and nitrogen polarity layers of GaN grown on sapphire
2003
A confocal Raman spectroscopic study was carried out on either side of an intentionally grown GaN inversion domain boundary between a pair of strips with opposite (Ga- or N-) polarity. It is shown that the Raman spectra on the N-polarity side displays an A1(TO) mode, prohibited by symmetry considerations, meanwhile on Ga-polarity material this peak is absent, indicating a lower density of defects present in this region. The Raman spectra reveal that in the lateral direction, the change in structural quality accross the inversion domain boundary is rather continuous and extends along 4 ± 1 μm. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)