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The Purcell effect dependence on the excitation power is studied in photonic crystal microcavity lasers embedding InAs/InP quantum wires. In the case of non-lasing modes, the Purcell effect has low dependence on the optical pumping, attributable to an exciton dynamics combining free and localized excitons. In the case of lasing modes, the influence of the stimulated emission makes ambiguous the determination of the Purcell factor. We have found that this ambiguity can be avoided by measuring the dependence of the decay time on the excitation power. These results provide insights in the determination of the Purcell factor in microcavity lasers. © 2013 AIP Publishing LLC., We want to acknowledge financial support from the Spanish MICINN through grants (Nos. S-0505-TIC-0191, TEC2008-06756-C03-01/-03, TEC2011-29045-C04-03, TEC2011-29120-C05-01/04, and CAM S2009ESP-1503). J.C.-F. thanks the Spanish MCI for his FPI grant (No. BES-2006-12300).

We have studied the temperature dependence of the photoluminescence of a single layer of InAs/InP(001) self-assembledquantum wires emitting at 1.5 μm. The non-radiative mechanisms responsible for the quenching of the emission band have been identified. The exciton dynamics has been investigated using time resolved photoluminescence measurements. The results have been explained through the interplay between free excitons and localized states (arising from size fluctuations in the quantum wires)., We want to acknowledge financial support from the Spanish MICINN through Grants: TEC 2005-05781-C03-03, S-0505-TIC-0191, TEC2008-06756-C03, Consolider-Ingenio 2010 QOIT (CSD2006-0019), and CAM S2009ESP-1503. The main author, J.C.-F., thanks also the Spanish MCI for his FPI grant BES-2006-12300.

We have developed a growth process that leads to the direct formation of self-assembled InAs quantum dots on InP(001) by solid-source molecular beam epitaxy avoiding the previous formation of quantum wires usually obtained by this technique. The process consists of a periodically alternated deposition of In and As correlated with InAs(4×2)(2×4) surface reconstruction changes. Based on the results obtained by in situ characterization techniques, we propose that the quantum dots formation is possible due to the nucleation of In droplets over the InAs(4×2) surface during the In deposition step and their subsequent crystallization under the As step. The authors acknowledge the financial support of the Spanish MICINN (TEC2008-06756-C03-01), Consolider-QOIT (CSD2006-0019), and CAM (S-505/ESP/000200). P.A.G. and A.R. thank the I3P program. B.A. thanks the Ramón y Cajal program.

http://link.aip.org/link/?JAPIAU/103/056108/1, We demonstrated the effect of reactive ion beam etching (RIBE) process on the PL properties of CdTe/sapphire metal organic vapor phase epitaxy layers. At optimum conditions, the RIBE attack does not make significant morphological changes but it results in an increase of the concentration of acceptor impurities. This was revealed by an increase of the overall photoluminescence (PL) intensity and, simultaneously, a decrease of the PL decay time, more important on the low energy side of PL spectrum due to the recombination of carriers in acceptor pairs., This work was supported by the Spanish projects TEC-2005-05781-C03-03 and CAM SENSORCDT S-0505/MAT/0209.

We present a study of the structural and optical properties of InAs quantum dots formed in a low density template of nanoholes fabricated by droplet epitaxy on GaAs (001). The growth conditions used here promote the formation of isolated quantum dots only inside the templated nanoholes. Due to the good optical quality and low density of these nanostructures, their ensemble and individual emission properties could be investigated and related to the particular growth method employed and the quantum dot morphology., The authors gratefully acknowledge the financial support by the Spanish MEC and CAM through project Nos. TEC-2005-05781-C03-01/-03 and NAN2004-09109-C04-01/-03, by the Consolider-Ingenio 2010 CSD2006-0019 and S-505/ESP/000200, and by the European Commission through SANDIE Network of Excellence No. NMP4-CT-2004- 500101 . P.A.G. thanks the I3P program.

A compact minicryostat has been well adapted on the hard x-ray microprobe ID22 of the European Synchrotron Radiation Facility. For variable low-temperature investigations, its special technical design provides precise scanning microscopy and allows easy access for multiple detection modes. Based on x-ray excited optical luminescence technique on the micrometer scale, details of the equipment, its temperature calibration, and typical results are described. Data collections from InAs quantum heterostructures support the excellent thermal performance of the novel cryogenic device., Special thanks are due to Michele Soulier and Yves Dabin for the design of the mechanical interface used on the sample stage. The authors are also grateful to Remi Tucoulou as well as Isabelle Letard for their useful help.

We present a Raman study of the vibrational modes in InAs/InP (001) quantum wires. The energy of the observed phonon modes evidences the confinement properties of the wires, their strain anisotropy and the effect of atomic intermixing. Resonance effects in confined and interface phonons are discussed for excitation in the vicinity of the E1 critical point. The observed vibrations and their variation with sample characteristics are in agreement with the conclusions of previous structural and optical characterization performed in the same samples. © 2007 American Institute of Physics.

The size and emission wavelength of self-assembled InAs∕InP(001) quantum wires (QWrs) is affected by the P∕As exchange process. In this work, we demonstrate by in situ stress measurements that P∕As exchange at the InAs∕InP interface depends on the surface reconstruction of the InAs starting surface and its immediate evolution when the arsenic cell is closed. Accordingly, the amount of InP grown on InAs by P∕As exchange increases with substrate temperature in a steplike way. These results allow us to engineer the size of the QWr for emission at 1.3 and 1.55 μm at room temperature by selecting the range of substrate temperatures in which the InP cap layer is grown., This work was financed by Spanish MCyT under NANOSELF project (TIC2002-04096) and by NANOMAT project of the EC Growth Program, Contract No. G5RD-CT-2001-00545. One of the authors (D.F.) thanks the Spanish MECyD for funds. The authors also thank the Junta de Andalucía (PAI research group TEP-0120). TEM measurements were carried out in the DME-SCCYT and UCM.

Size and spatial distribution homogeneity of nanostructures is greatly improved by making stacks of nanostructures separated by thin spacers. In this work, we present in situ and in real time stress measurements and reflection high-energy electron diffraction observations and ex situ transmission electron microscopy (TEM) characterization of stacked layers of InAs quantum wires (QWRs) separated by InP spacer layers, d(InP), of thickness between 3 and 20 nm. For d(InP), This work was financed by Spanish MCyT under NANOSELF project (TIC2002-04096), by NANOMAT project of the EC Growth Program (No. G5RD-CT-2001-00545) by Junta de Andalucía (TEP-0120). TEM measurements were carried out in the DME-SCCYT and UCM.