Effect of Thermal Annealing on the Photoluminescence Properties of a GaInNAs/GaAs Single Quantum Well
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Effect of Thermal Annealing on the Photoluminescence Properties of a GaInNAs/GaAs Single Quantum Well Laurent Grenouillet, Catherine Bru-Chevallier and Gérard Guillot Laboratoire de Physique de la Matière (UMR CNRS 5511), INSA Lyon, 20 avenue A. Einstein, 69621 Villeurbanne Cedex, France Philippe Gilet, Philippe Ballet, Philippe Duvaut, André Chenevas-Paule and Alain Million LETI/CEA-G – DOPT, 17 avenue des Martyrs, 38054 Grenoble Cedex 9, France ABSTRACT We report on the effect of thermal annealing on the photoluminescence properties of a Ga0.65In0.35N0.02As0.98/GaAs single quantum well. Thermal annealing is shown to decrease the strong nitrogen-induced localization effects observed at low temperatures and to reduce the full width at half maximum of the emission peak. It also induces a strong blue shift of the emission peak energy, which is thought not to arise from an In-Ga interdiffusion alone, as it is much larger than in a nitrogen-free reference single quantum well.
INTRODUCTION The GaInNAs semiconductor alloy is being intensively studied for both its fundamental properties and its potential for 1.3 µm optoelectronic device applications. Recently, the first 1.3 µm electrically-pumped vertical cavity surface emitting laser based on GaAs and containing GaInNAs/GaAs quantum wells as the active layers has been reported [1], confirming that GaInNAs is a very promising material. However, the N incorporation in GaInAs induces a degradation of the photoluminescence (PL) efficiency. A rapid thermal annealing (RTA) is usually carried out to enhance the optical properties. Nevertheless, the mechanisms induced by RTA are not yet fully understood. We focused our study on the PL spectrum temperature dependence of a GaInNAs/GaAs single quantum well (SQW). We have shown previously [2] that the PL emission at low temperatures comes preferentially from strongly localized excitons located below the band edge. The consecutive anomalous temperature dependence of the PL peak parameters is first reviewed and then investigated as thermal annealing proceeds, in order to get a better insight into the mechanisms involved during RTA. The same study has been performed in a nitrogen-free GaInAs/GaAs reference SQW for comparison purposes. A decrease of the localization effects is evidenced in the GaInNAs/GaAs SQW as annealing time increases. The RTA also induces a blue shift of the PL peak, which is much larger in the SQW with nitrogen than in the nitrogen-free reference SQW. The origin of such a behavior will be discussed.
EXPERIMENTAL DETAILS The 7 nm Ga0.65In0.35N0.02As0.98/GaAs SQW and the 7 nm nitrogen-free Ga0.65In0.35As/GaAs reference SQW were grown by gas source molecular beam epitaxy equipped G6.3.1
with a radio frequency plasma source to decompose N2 into N active species. Both samples consist of a 350 nm thick GaAs buffer layer grown at 580 °C, the SQW grown at 400 °C and a GaAs cap layer. The indium and nitrogen contents were determined by high resolution X-ray diffraction measurements. More information can be found in refer
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