High-resolution cathodoluminescence hyperspectral imaging of nitride nanostructures

Hyperspectral cathodoluminescence imaging provides spectrally and spatially resolved information on luminescent materials within a single dataset. Pushing the technique toward its ultimate nanoscale spatial limit, while at the same time spectrally dispersing the collected light before detection, increases the challenge of generating low-noise images. This article describes aspects of the instrumentation, and in particular data treatment methods, which address this problem. The methods are demonstrated by applying them to the analysis of nanoscale defect features and fabricated nanostructures in III-nitride-based materials

A calibrated UV LED light source for photocatalytic experimentation

Photocatalysis is an evolving field that has a potential to become a cost effective water cleaning method. One of the most studied photocatalysts is Titanium Dioxide (TiO2). It has a high activity in response to UV wavelengths but almost no activity in the visible region of the spectrum. The activity changes rapidly between roughly 340 and 370 nm although this can be modified by doping. This region of the spectrum corresponds to the current lower limit of high efficiency LEDs. This presents a challenge in the use of UV LEDs for commercially viable photocatalysis and makes accurate comparisons of experimental data between different research groups essential. This paper presents a photocatalytic test reactor that provides a calibrated light source and pre-defined test conditions to remove as many sources of uncertainty as possible to improve data comparability. The test reactor provides a selectable intensity of up to 1.9 kW/m2 at the photocatalyst surface. The comparability of the results is achieved through the use of pre-calibration and control electronics that minimizes the biggest source of uncertainty – intensity variation between individual LEDs. The system devised reduces the intensity variation between systems by a factor of 11.6

Fabrication of high-aspect ratio GaN nanostructures for advanced photonic devices

This dataset is the result of an investigation into the impact of the temperature and pressure on the fabrication of Gallium Nitride nanostructures. The dataset contains data acquired from etched nanorods and nanopores.The data was acquired using a Hitachi S-4300 scanning electron microscope (SEM). The secondary electron (SE) images were produced using the manufacturer-supplied software. Figure numbers in the data file descriptions refer to the Microelectronic Engineering article by Le Boulbar et al. (2016) referenced in the related publications section.The height and diameter of the nanostructure were extracted from the SE image. Measurements were taken on more than five nanostructures to obtain representative and accurate dimensions.An Inductively Coupled Plasma (ICP) (Oxford Instrument 100 Cobra) were used for the dry-etching process

Waveguide integrated GaN distributed Bragg reflector cavity using low-cost nanolithography

This work presents the design, fabrication and measurement of gallium nitride (GaN) distributed Bragg reflector cavities integrated with input and output grating couplers. The devices are fabricated using a new, low-cost nanolithography technique: displacement Talbot lithography combined with direct laser writing lithography. The finite-difference time-domain method has been used to design all the components and measured and modelled results show good agreement. Such devices have applications in GaN integrated photonics and biosensing.</p