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The properties of InGaAsN V-groove quantum wires (QWRs) -both untreated and irradiated with atomic hydrogen- are probed via micro-magneto-photoluminescence (PL) and polarization-dependent PL. As generally observed in dilute-nitride materials, H irradiation is found to fully passivate nitrogen, thus allowing us to accurately assess -and to precisely control- the effects of N incorporation in the QWRs. [ABSTRACT FROM AUTHOR]

The influence of nitrogen cluster states on the conduction band (CB) structure of GaAs1-xNx is probed by measuring the effective mass and gyromagnetic ratio of electrons for x < 0.7%. An unusual compositional dependence of these two important CB parameters is found. Such behaviors are well reproduced by a modified k·p model taking into account a non-monotonic loss of Γ character of the CB minimum due to multiple crossings between the red-shifting conduction band edge and N cluster states. As well, sudden variations in the electron mass can be externally induced by applying a hydrostatic pressure, which brings the upward moving CB edge into interaction with N states, which at ambient pressure are resonant with the GaAs1-xNx CB continuum. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Stacked InAs/GaAs quantum dots (QDs) have been hydrogenated at different doses and their electronic properties investigated by photoluminescence, PL. In the as grown samples it has been found that: (a) The concentration of non radiative defects increases with decreasing the barrier width of the stack; (b) the electronic interaction between separate layers is already effective for 30 nm GaAs barriers; (c) In and Ga interdiffusion take place during the growth of QD layers. In the hydrogenated samples, an increase in the PL efficiency is observed, higher at room temperature, and attributed to passivation of carrier traps in the QDs. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The GaP1-xNx conduction band is investigated experimentally (by excitation photoluminescence) and theoretically (by pseudopotential supercells) for N concentrations up to x=3.5% and photon energies ranging from the optical absorption edge to 3.2 eV. With increasing x: (i) a direct-like absorption edge develops smoothly and red-shifts rapidly overtaking energy-pinned cluster states; (ii) a broad absorption plateau appears between the X1c and the Γ1c critical points of GaP; (iii) the Γ1c absorption edge broadens and gradually disappears. Empirical pseudopotential calculations for GaP1-xNx random alloy supercells account well for all the PLE results by considering N induced changes in the valence band overlooked so far. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]