Comprehensive Model for the Transformation of Zinc Nitride Metastable Layers.

In this work, we performed systematic studies on the oxidation of zinc nitride metastable layers using a climate chamber with controlled temperature and relative humidity. The electrical properties of the samples were in situ analyzed using a programmable microprocessor with a voltage divider, while the structural and optical properties were ex situ measured by scanning electron microscopy, elastic recoil detection analysis, and spectroscopic ellipsometry. Our results show that zinc nitride transformation proceeds in a top-down way, with a progressive substitution of N by O, which leads to the formation of pores and a remarkable swelling effect.

Breast cancer biomarker detection through the photoluminescence of epitaxial monolayer MoS flakes.

In this work we report on the characterization and biological functionalization of 2D MoS flakes, epitaxially grown on sapphire, to develop an optical biosensor for the breast cancer biomarker miRNA21. The MoS flakes were modified with a thiolated DNA probe complementary to the target biomarker. Based on the photoluminescence of MoS, the hybridization events were analyzed for the target (miRNA21c) and the control non-complementary sequence (miRNA21nc).

Enhanced electrochemiluminescence by ZnO nanowires for taurine determination.

A novel electrochemiluminescence (ECL) sensor for the sensitive detection of taurine was developed. Taurine contains an aliphatic amine that gives it co-reactant properties. The ECL response of the taurine/[Ru(bpy)] system was analyzed on two different electrodes surfaces, screen-printed graphene and gold electrodes, before and after modification with ZnO nanowires (ZnO NWs).

Energy Transfer and Interference by Collective Electromagnetic Coupling.

The physics of collective optical response of molecular assemblies, pioneered by Dicke in 1954, has long been at the center of theoretical and experimental scrutiny. The influence of the environment on such phenomena is also of great interest due to various important applications in, e.g.

Photoluminescence enhancement of monolayer MoS using plasmonic gallium nanoparticles.

2D monolayer molybdenum disulphide (MoS) has been the focus of intense research due to its direct bandgap compared with the indirect bandgap of its bulk counterpart; however its photoluminescence (PL) intensity is limited due to its low absorption efficiency. Herein, we use gallium hemispherical nanoparticles (Ga NPs) deposited by thermal evaporation on top of chemical vapour deposited MoS monolayers in order to enhance its luminescence. The influence of the NP radius and the laser wavelength is reported in PL and Raman experiments.

High Ultraviolet Absorption in Colloidal Gallium Nanoparticles Prepared from Thermal Evaporation.

New methods for the production of colloidal Ga nanoparticles (GaNPs) are introduced based on the evaporation of gallium on expendable aluminum zinc oxide (AZO) layer. The nanoparticles can be prepared in aqueous or organic solvents such as tetrahydrofuran in order to be used in different sensing applications. The particles had a quasi mono-modal distribution with diameters ranging from 10 nm to 80 nm, and their aggregation status depended on the solvent nature.

Gallium plasmonic nanoparticles for label-free DNA and single nucleotide polymorphism sensing.

A label-free DNA and single nucleotide polymorphism (SNP) sensing method is described. It is based on the use of the pseudodielectric function of gallium plasmonic nanoparticles (GaNPs) deposited on Si (100) substrates under reversal of the polarization handedness condition. Under this condition, the pseudodielectric function is extremely sensitive to changes in the surrounding medium of the nanoparticle surface providing an excellent sensing platform competitive to conventional surface plasmon resonance.

Immunosensing platform based on gallium nanoparticle arrays on silicon substrates.

Gallium nanoparticles (GaNPs) of different sizes are deposited on Si(100) substrates by thermal evaporation. Through ellipsometric analysis, it is possible to investigate the plasmonic effects in the GaNPs and exploit them to develop biosensors. The excitation of the resonant modes for certain incidence angles leads to negative values of the imaginary part of the pseudodielectric function (<εi>) obtained in ellipsometry.

Optical sensors based on III-nitride photodetectors for flame sensing and combustion monitoring.

Combustion control requires visible photodetectors to sense the CH* CL emission at 430 nm that combined with a visible-blind UV photodetector allows us to obtain the OH*/CH* ratio. UV-visible P-InGaN/GaN multiple quantum well-N photodiodes with 15-18 mm2 areas were fabricated to conduct OH* (308 nm) and CH* CL detection without external filters. Bandpass detectors at 230-390 nm and 360-450 nm presented linear responses over five decades and rejection ratios >10(3) at 430 and 308 nm, respectively.