Weiming Guo

Room temperature operation of GaAsP(N)/GaP(N) quantum well based light-emitting diodes: Effect of the incorporation of nitrogen

This letter deals with the electroluminescence emission at room temperature of two light-emitting diodes on GaP substrate, based on ternary GaAsP/GaP and quaternary GaAsPN/GaPN multiple quantum wells. In agreement with tight-binding calculations, an indirect band gap is demonstrated from the temperature-dependent photoluminescence for the first structure. High efficiency photoluminescence is then observed for the second structure. Strong electroluminescence and photocurrent are measured from the diode structures at room temperature at wavelengths of 660 nm (GaAsP/GaP) and 730 nm (GaAsPN/GaPN). The role of the incorporation of nitrogen on the optical band gap and on the nature of interband transitions is discussed.

Structural and optical analyses of GaP/Si and (GaAsPN/GaPN)/GaP/Si nanolayers for integrated photonics on silicon

We report a structural study of molecular beam epitaxy-grown lattice-matched GaP/Si(0 0 1) thin layers with an emphasis on the interfacial structural properties, and optical studies of GaAsP(N)/GaP(N) quantum wells coherently grown onto the GaP/Si pseudo substrates, through a complementary set of characterization tools. Room temperature photoluminescence at 780 nm from the (GaAsPN/GaPN) quantum wells grown onto a silicon substrate is reported. Despite this good property, the time-resolved photoluminescence measurements demonstrate a clear influence of non-radiative defects initiated at the GaP/Si interface. It is shown from simulations, how x-ray diffraction can be used efficiently for analysis of antiphase domains. Then, qualitative and quantitative analyses of antiphase domains, micro-twins, and stacking faults are reported using complementarity of the local transmission electron microscopy and the statistical x-ray diffraction approaches.

Theoretical study of highly strained InAs material from first-principles modelling : application to an ideal QD

We study the properties of highly strained InAs material calculated from first-principles modelling using ABINIT packages. We first simulate the characteristics of bulk InAs crystals and compare them with both experimental and density functional theory results. Secondly, we focus our attention on the strain effects on InAs crystals with a gradual strain reaching progressively the lattice matched parameters of InP, GaAs and GaP substrates. Section 4 is dedicated to the study of a hypothetical spherical InAs/GaP quantum dot (QD). The effect of hydrostatic deformations for both InAs zinc-blende phase and InAs rocksalt phase is discussed. Section 5 is devoted to the dependence of the lattice parameter aoz versus aox (aoy), Γ gap energies and band line-ups at the Γ point for biaxial deformations and interfacial structures. Ab initio results are compared with the empirical calculations which reveal nonlinear behaviour of the conduction band for highly strained InAs material.

Coherent integration of photonics on silicon through the growth of nanostructures on GaP/Si

Selected results obtained in the framework of MBE grown nanostructure for photonics on silicon are repsented in this paper. We present first a comprehensive study of GaAsPN/GaPN quantum wells (QWs) grown onto GaP substrates, in the light of a comparison with their N-free GaAsP/GaP QWs counterpart system. High density of small InGaAs/GaP Quantum Dots are presented next with their PL properties. Finally, RT photoluminescence properties of GaAsPN/GaPN QWs onto Si substrate are presented and discussed in term of carrier injection efficiency. However, for future development, optical properties of the active area must be improved and are tightly bound to the structural perfection of the GaP/Si template layer. To address this point, structural analyses including X-Ray Diffraction (lab setup and synchrotron) and Transmission Electron Microscopy have been performed, with a particular care for typical III-V/Si defect characterisation. First results of Si buffer layer growth are also presented as a perspective for future low defect MBE grown GaP/Si template layers.