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Dependent Photoluminescence (dependent + photoluminescence)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

Photoluminescence and Hall studies of GaN:Fe and (Ga,Fe)N:Mg layers

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2007
M. Wegscheider
Abstract Temperature dependent photoluminescence (PL) in the ultraviolet (UV) regime and Hall measurements at room temperature have been performed on Metal-Organic-Chemical-Vapour-Deposition (MOCVD) grown GaN:Fe and (Ga,Fe)N:Mg layers. PL measurements were employed in order to study the dopants' influence on the near-band edge excitonic emission and their tendency to provoke the formation and suppression of defects or incorporation of impurities. For their identification and for the understanding of the PL spectra the evaluation of the free carrier concentrations via Hall measurements were necessary. Depending on the iron concentration of the (Ga,Fe)N layers, the near-band edge emission goes through two different stages: at low Fe-concentration no excitonic emission can be seen whereas with higher doping levels, excitonic features develop. The (Ga,Fe)N films exhibit n-type behaviour. The Mg codoped samples show strong Mg and defect related luminescence bands, whose occurrence and intensity also strongly depends on whether high or low Fe concentration is present. The (Ga,Fe)N:Mg layers were semi insulating. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

InAs/InP quantum dot photonic crystal microcavities

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2006
Simon Frédérick
Abstract We examine the optical mode structure of two-dimensional, photonic crystal microcavities based on triple missing hole defects in hexagonal symmetry, etched air-hole, suspended InP membranes. Polarisation dependent photoluminescence from InAs/InP quantum dots embedded within the cavities is used to explore mode energies and quality factors, Q, as a function of cavity design parameters. Optimised Q values are in excess of 7,500 for the modified y-dipole mode. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Optimizing the internal quantum efficiency of GaInN SQW structures for green light emitters

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2006
D. Fuhrmann
Abstract GaxIn1,xN/GaN single quantum well (QW) structures emitting in the range of 450 nm to 620 nm have been grown by MOVPE. Temperature and excitation power dependent photoluminescence (PL) was used to determine the internal quantum efficiency (IQE) for these structures. For the blue emitting QWs high IQE values on the order of 60% were achieved. Due to a reduced growth temperature, reduced growth rate and increased V/III ratio we obtained QWs with good morphology and high In content above 25%. Thinner QWs with high In content showed a clear improvement of IQE compared to QW-structures with larger thickness but smaller In-content emitting at the same wavelength. Between ,peak = 460 nm and 530 nm we observed a slight reduction in IQE with values of 58% at 490 nm and 40% at 525 nm. But towards ,peak = 620 nm IQE decreased due to the electric field induced separation of the electron and hole wavefunction down to 1%. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Investigations of p-type signal for ZnO thin films grown on (100) GaAs substrates by pulsed laser deposition

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2006
D. J. Rogers
Abstract In this work we investigated ZnO films grown on semi-insulating (100) GaAs substrates by pulsed laser deposition. Samples were studied using techniques including X-ray diffraction (XRD), scanning electron microscopy, atomic force microscopy, Raman spectroscopy, temperature dependent photoluminescence, C-V profiling and temperature dependent Hall measurements. The Hall measurements showed a clear p-type response with a relatively high mobility (,260 cm2/V s) and a carrier concentration of ,1.8 × 1019 cm,3. C-V profiling confirmed a p-type response. XRD and Raman spectroscopy indicated the presence of (0002) oriented wurtzite ZnO plus secondary phase(s) including (101) oriented Zn2As2O7. The results suggest that significant atomic mixing was occurring at the film/substrate interface for films grown at substrate temperatures of 450 ºC (without post-annealing). (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Do we really need another PL study of CuInSe2?

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2004
Susanne Siebentritt
Abstract A detailed composition, intensity and temperature dependent photoluminescence (PL) study of CuInSe2 has been performed to obtain data on defects, directly comparable to the defects in CuGaSe2, prepared under the same conditions. Epitaxial films are grown by metal organic vapour phase epitaxy on GaAs. The PL study reveals three shallow defects, which are responsible for the doping behaviour in CuInSe2: two acceptors, 40 and 60 meV deep, and a donor, approximately 12 meV deep. The shallower acceptor dominates for low or no Cu-excess, whereas the deeper one dominates material grown under high Cu-excess. These defects and their compositional dependence are the same as observed in CuGaSe2. Thus no fundamental difference concerning the shallow defects exists between these two materials. [source]