Effect of carrier transfer on the PL intensity in self-assembled In (Ga) As/GaAs quantum rings

We present results concerning the carrier transfer between In(Ga)As quantum rings in a stacked multilayer structure, which is characterised by a bimodal size distribution. This transfer of carriers explains the observed temperature behaviour of diode lasers based on that kind of stacked layer structures. The inter-ring carrier transfer can be possible by phonon assisted tunnelling from the ground state of the smallring family towards the big-ring family of the bimodal size distribution. This process is thermally activated in the range 40–80 K.This work was partially supported by Spanish MCyT Nanoself I and II projects TIC2002-04096-C03 and TEC2005-05781-C03-03, the SANDiE Network of excellence (Contract No. NMP4-CT-2004-500101) and the AECI Spain-Tunisia bilateral research action No. 2/04/R.Peer reviewe

Kinetics of exciton photoluminescence in type-II semiconductor superlattices

The exciton decay rate at a rough interface in type-II semiconductor superlattices is investigated. It is shown that the possibility of recombination of indirect excitons at a plane interface essentially affects kinetics of the exciton photoluminescence at a rough interface. This happens because of strong correlation between the exciton recombination at the plane interface and at the roughness. Expressions that relate the parameters of the luminescence kinetics with statistical characteristics of the rough interface are obtained. The mean height and length of roughnesses in GaAs/AlAs superlattices are estimated from the experimental data.Comment: 3 PostScript figure

Non-covalent biofunctionalization of single-walled carbon nanotubes via biotin attachment by π-stacking interactions and pyrrole polymerization

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Electrochemical Characterization of Biotin Functionalized and Regular Single-Walled Carbon Nanotube Coatings. Application to Amperometric Glucose Biosensors

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Amperometric Biosensors Based on Biotinylated Single-Walled Carbon Nanotubes

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Spin Relaxation Time in InAlAs/AlGaAs Quantum Dots

We report systematic temperature dependent measurements of spin relaxation time in self-assembled In0.72Al0.28As/Al0.28Ga0.72As quantum dots by continuous-wave photoluminescence. The degree of circular polarization decreases as a function of temperature. The spin relaxation time tS is deduced from the circular polarization degree using a three dimensional pseudo- spin precession model. The spin relaxation time decreases rapidly from few hundred picoseconds at 10 K to few tens picoseconds at 85 K. This large change of the spin relaxation time is explained in terms of acoustic phonon emission mechanism