Hanbury-Brown and Twiss Intensity Correlations of Parabosons

This paper shows that in intensity correlation measurements there will be clear and unambiguous signals that new-physics particles are, or aren't, parabosons. For a parabosonic field in a dominant single-mode, there is a diagonal P-representation in the "even and odd coherent states" basis. It is used to analyze zero-time-interval intensity correlations of parabosons in a maximum-entropic state. As the mean number of parabosons decreases, there is a monotonic reduction to (2/p) of the constant bosonic ``factor of two'' proportionality of the second-order versus the squared first-order intensity correlation function.Comment: 16 pages; version 4 to add simple p-independent recursion relatio

Solution processed semiconductor alloy nanowire arrays for optoelectronic applications

In this dissertation, we use ZnO nanowire as a model system to investigate the potential of solution routes for bandgap engineering in semiconductor nanowires. Excitingly, successful Mg-alloying into ZnO nanowire arrays has been achieved using a two-step sequential hydrothermal method at low temperature (\u3c155°C) without using post-annealing process. Evidently, both room temperature and 40 K photoluminescence (PL) spectroscopy revealed enhanced and blue-shifted near-band-edge ultraviolet (NBE UV) emission in the Mg-alloyed ZnO (ZnMgO) nanowire arrays, compared with ZnO nanowires. The specific template of densely packed ZnO nanowires is found to be instrumental in achieving the Mg alloying in low temperature solution process. By optimizing the density of ZnO nanowires and precursor concentration, 8-10 at.% of Mg content has been achieved in ZnMgO nanowires. ^ Post-annealing treatment is conducted in oxygen-rich and oxygen-deficient environment at different temperatures and time durations on silicon and quartz substrates in order to study the structural and optical property evolution in ZnMgO nanowire arrays. Vacuum annealed ZnMgO nanowires on both substrates retained their hexagonal structures and PL results showed the enhanced but red-shifted NBE UV emission compared to ZnO nanowires with visible emission nearly suppressed, suggesting the reduced defects concentration and improvement in crystallinity of the nanowires. On the contrast, for ambient annealed ZnMgO nanowires on silicon substrate, as the annealing temperature increased from 400°C to 900°C, intensity of visible emission peak across blue-green-yellow-red band (∼400-660 nm) increased whereas intensity of NBE UV peak decreased and completely got quenched. This might be due to interface diffusion of oxidized Si (SiOx) and formation of (Zn,Mg)1.7SiO4 epitaxially overcoated around individual ZnMgO nanowire. On the other hand, ambient annealed ZnMgO nanowires grown on quartz showed a ∼6-10 nm blue-shift in NBE UV emission, indicating significantly enhanced inter-diffusion of Mg into ZnO nanowires in this oxygen-rich environment.^ The successfully developed solution process for semiconductor nanowires alloying has few advantages in low cost, large yield, environmental friendliness and low reaction temperature. This solution processed ZnMgO nanowire arrays could provide a new class of nanoscale building blocks for various optoelectronic devices in UV lighting and visible solar energy harvesting.

Hierarchical Assembly of Multifunctional Oxide-based Composite Nanostructures for Energy and Environmental Applications

Composite nanoarchitectures represent a class of nanostructured entities that integrates various dissimilar nanoscale building blocks including nanoparticles, nanowires, and nanofilms toward realizing multifunctional characteristics. A broad array of composite nanoarchitectures can be designed and fabricated, involving generic materials such as metal, ceramics, and polymers in nanoscale form. In this review, we will highlight the latest progress on composite nanostructures in our research group, particularly on various metal oxides including binary semiconductors, ABO<sub>3</sub>-type perovskites, A<sub>2</sub>BO<sub>4</sub> spinels and quaternary dielectric hydroxyl metal oxides (AB(OH)<sub>6</sub>) with diverse application potential. Through a generic template strategy in conjunction with various synthetic approaches—such as hydrothermal decomposition, colloidal deposition, physical sputtering, thermal decomposition and thermal oxidation, semiconductor oxide alloy nanowires, metal oxide/perovskite (spinel) composite nanowires, stannate based nanocompostes, as well as semiconductor heterojunction—arrays and networks have been self-assembled in large scale and are being developed as promising classes of composite nanoarchitectures, which may open a new array of advanced nanotechnologies in solid state lighting, solar absorption, photocatalysis and battery, auto-emission control, and chemical sensing