This paper discusses the fundamentals, applications, potential, limitations, and future perspectives of polarized light reflection techniques for the characterization of materials and related systems and devices at the nanoscale. These techniques include spectroscopic ellipsometry, polarimetry, and reflectance anisotropy. We give an overview of the various ellipsometry strategies for the measurement and analysis of nanometric films, metal nanoparticles and nanowires, semiconductor nanocrystals, and submicron periodic structures. We show that ellipsometry is capable of more than the determination of thickness and optical properties, and it can be exploited to gain information about process control, geometry factors, anisotropy, defects, and quantum confinement effects of nanostructures.

Using Raman backscattering spectroscopy we have observed six local vibrational modes in as-grown state-of-the-art nominally undoped zinc oxide single crystals. The local vibrational modes are located at $\nu =2854$, 2890, 2918, 2948, 2988, and $3096{\mathrm{c}\mathrm{m}}^{-1}$. Some specimens were annealed up to $950°\mathrm{C}$ to remove hydrogen. A subsequent Raman backscattering measurement revealed that the local vibrational modes disappeared. This establishes that the observed local vibrational modes are caused by the presence of hydrogen in the ZnO crystals.

A p-type transparent conductive oxide (TCO) was synthesised by codoping of poorly conducting chromium oxide (Cr₂O₃) with magnesium and nitrogen. We demonstrated that the codoping produced a TCO with good figure of merit despite using spray pyrolysis for deposition. The nitrogen enhances the specular transparency of the films in the visible range (400-700 nm), and Mg improves the conductivity while retaining the p-type character of the material. Co-doping with both elements produces a p-type oxide with a low resistivity of 3 Ω cm and transmission up to 65% for a 150 nm thick film. A comparison with other known p-type materials is given.

We present experimental evidence of electron-beam-induced diffusion of O and H in unintentionally doped n-type GaN grown on a sapphire substrate. Impurity diffusion was investigated using cathodoluminescence kinetics and imaging at 4 and 300 K and by wavelength dispersive x-ray analysis. The results illustrate the significance of electron-beam-induced electromigration in wide band gap semiconductors, confirm the roles of ${\mathrm{O}}_{\mathrm{N}}^{\mathrm{•}}$ in bound exciton, donor-acceptor pair and yellow emissions and suggest the involvement of ${\mathrm{O}}_{\mathrm{N}}^{\mathrm{•}}$ and hydrogenated gallium vacancies in the previously unexplained blue luminescence.

The rapidly expanding fields of bioelectronics, and biological interfaces with electronic sensors and stimulators, are placing an increasing demand on candidate materials to serve as robust surfaces that are both biocompatible, stable and electroconductive. Amongst conductive polymers, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a promising material in biomedical research due to its appropriate stability and high conductivity, however its intrinsic solubility requires a crosslinking process that can limit its conductivity and biocompatibility. Poly(ethylene glycol) is known to be a suitably anti-immunogenic moiety and its derivatives have been widely used for biomedical applications. In this study we investigate the application of poly(ethylene glycol)diglycidyl ether (PEGDE) as an effective crosslinker and conductive filler for PEDOT:PSS. From our interpretation of XPS analysis we hypothesise that the crosslinking reaction is occurring via the epoxy ring of PEGDE interacting with the sulfonic groups of excel PSS chains, which reaches a saturation at 3 w/v% PEGDE concentration. PEGDE crosslinked films did not disperse in aqueous environments, had enhanced electrical conductivity and imparted a significant degree of hydrophilicity to PEDOT:PSS films. This hydrophilicity and the presence of biocompatible PEGDE led to good cell viability and a significantly increased degree of cell spreading on PEDOT:PSS films. In comparison to widely reported chemical crosslinking via glycidoxy propyltrimethoxysilane (GOPS), this original crosslinking yields a highly hydrophilic 2D film substrate with increased electroconductive and biocompatibility properties, resulting in a next-generation formulation for bioengineering applications.