Elements Of X Ray Diffraction

We have observed size effects in the structural phase transition of submicron vanadium dioxide precipitates in silica. The VO 2 nanoprecipitates are produced by the stoichiometric coimplantation of vanadium and oxygen andsubsequent thermal processing. The observed size dependence in the transition temperature and hysteresis loops of the semiconductor-to-metal phase transition in VO 2 is described in terms of heterogeneous nucleation statistics with a phenomenological approach in which the density of nucleating defects is a power function of the driving force.

Size effects in the structural phase transition of VO2 nanoparticles

We calculate the binding energy of a hydrogenic donor impurity in a rectangular parallelepiped-shaped quantum dot (QD) in the framework of effective-mass envelope-function theory using the plane wave basis. The variation of the binding energy with edge length, position of the impurity, and external electric field is studied in detail. A finite potential model is adopted in our calculations. Compared with the infinite potential model [C. I. Mendoza et al., Phys. Rev. B 71, 075330 (2005)], the following results are found: (1) if the impurity is located in the interior of the QD, our results give a smaller binding energy than the infinite potential model; (2) the binding energies are more sensitively dependent on the applied electric field in the finite potential model; (3) the infinite potential model cannot give correct results for a small QD edge length for any location of the impurity in the QD; (4) some degeneracy is lifted when the dot is no longer cubic.

Binding energy of a hydrogenic donor impurity in a rectangular parallelepiped-shaped quantum dot : Quantum confinement and Stark effects

Enhancing optical anisotropy of crystals by optimizing bonding electron distribution in anionic groups

Development work was conducted on N+PN+PN+ Poly silicon light-emitting devices which are compatible with silicon-based integrated circuit technology. We discuss the emission characteristics of visible light by a monolithically integrated Poly-Si diode under reverse bias. With the structure of modified PN junctions, the carriers injection occurs through silicon slabs of only a few nanometer thick. The dominant role of non-radiative recombination at the N+ and P+ contacts is diminished by confining the injected carriers around the PN junction’s interface in which avalanche takes place. The current-dependent optical radiation presents a broad spectrum in the 400- to 900-nm range. Although the emission efficiency is low due to silicon’s indirect bandgap, it is advantageous to utilize these devices in all-silicon optoelectronic integrated circuits (OIC’s).

Anouar Jorio

Papers

Linear and nonlinear intra-conduction band optical absorption in (In,Ga)N/GaN spherical QD under hydrostatic pressure

Pressure-dependent of linear and nonlinear optical properties of (In,Ga)N/GaN spherical QD

Magnetic field effect on the polarizability of shallow donor in cylindrical quantum dot

Magnetic field and finite barrier-height effects on the polarizability of a shallow donor in a GaAs quantum wire

Graphene oxide/ZnO nanorods/graphene oxide sandwich structure: The origins and mechanisms of photoluminescence