Solid state UV emitters have many advantages over conventional UV sources. The (Al,In,Ga)N material system is best suited to produce LEDs and laser diodes from 400 nm down to 210 nm—due to its large and tuneable direct band gap, n- and p-doping capability up to the largest bandgap material AlN and a growth and fabrication technology compatible with the current visible InGaN-based LED production. However AlGaN based UV-emitters still suffer from numerous challenges compared to their visible counterparts that become most obvious by consideration of their light output power, operation voltage and long term stability. Most of these challenges are related to the large bandgap of the materials. However, the development since the first realization of UV electroluminescence in the 1970s shows that an improvement in understanding and technology allows the performance of UV emitters to be pushed far beyond the current state. One example is the very recent realization of edge emitting laser diodes emitting in the UVC at 271.8 nm and in the UVB spectral range at 298 nm. This roadmap summarizes the current state of the art for the most important aspects of UV emitters, their challenges and provides an outlook for future developments.

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We present a detailed study of the effects of dangling bond passivation and the comparison of different sulfide passivation processes on the properties of InGaN/GaN quantum-disk (Qdisk)-in-nanowire based light emitting diodes (NW-LEDs). Our results demonstrated the first organic sulfide passivation process for nitride nanowires (NWs). The results from Raman spectroscopy, photoluminescence (PL) measurements, and X-ray photoelectron spectroscopy (XPS) showed that octadecylthiol (ODT) effectively passivated the surface states, and altered the surface dynamic charge, and thereby recovered the band-edge emission. The effectiveness of the process with passivation duration was also studied. Moreover, we also compared the electro-optical performance of NW-LEDs emitting at green wavelength before and after ODT passivation. We have shown that the Shockley-Read-Hall (SRH) non-radiative recombination of NW-LEDs can be greatly reduced after passivation by ODT, which led to a much faster increasing trend of quantum efficiency and higher peak efficiency. Our results highlighted the possibility of employing this technique to further design and produce high performance NW-LEDs and NW-lasers.

Typical light‐emitting diodes (LEDs) have a form factor >(300 × 300) µm2. Such LEDs are commercially mature in illumination and ultralarge displays. However, recent LED research includes shrinking individual LED sizes from side lengths >300 µm to values <100 µm, leading to devices called micro‐LEDs. Their advent creates a number of exciting new application spaces. Here, a review of the principles and applications of micro‐LED technology is presented. In particular, the implications of reduced LED size in necessitating mitigation strategies for nonradiative device edge damage as well as the potential for higher drive current densities are discussed. The opportunities to integrate micro‐LEDs with electronics, and into large‐scale arrays, allow pixel addressable scalable integrated displays, while the small micro‐LED size is ideal for high‐speed modulation for visible light communication, and for integration into biological systems as part of optogenetic therapies.

Impact of oxygen annealing on high-k gate stack defects characterized by random telegraph noise Appl. Phys. Lett. 101, 122105 (2012) Graphene based field effect transistor for the detection of ammonia J. Appl. Phys. 112, 064304 (2012) Unipolar behavior of asymmetrically doped strained Si0.5Ge0.5 tunneling field-effect transistors

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In this paper we describe the use of electron backscatter diffraction (EBSD) mapping and electron channeling contrast imaging-in the scanning electron microscope-to study tilt, atomic steps and dislocations in epitaxial GaN thin films. We show results from a series of GaN thin films of increasing thickness and from a just coalesced epitaxial laterally overgrown GaN thin film. From our results we deduce that EBSD may be used to measure orientation changes of the order of 0.02 degrees, in GaN thin films. As EBSD has a spatial resolution of approximate to 20 nm, this means we have a powerful technique with which to quantitatively map surface tilt. We also demonstrate that electron channeling contrast images may be used to image tilt, atomic steps, and threading dislocations in GaN thin films

We report an inexpensive nanoscale patterning process for epitaxial lateral overgrowth (ELOG) in AlN layers grown by metal organic vapour phase epitaxy (MOVPE) on sapphire. The pattern was produced by an inductively coupled plasma etch using a self-assembled monolayer of silica spheres on AlN as the lithographic mask. The resulting uniform 1 [small mu ]m length rod structure across a wafer showed a massive reduction in threading dislocations (TDs) when annealed at 1100 [degree]C. Overgrowing homoepitaxial AlN on top of the nanorods, at a temperature of 1100 [degree]C, produced a crack free coalesced film with approximately 4 [small mu ]m of growth, which is formed at a much lower temperature compared to that typically required for microscale ELOG. The improved crystal quality, in terms of TD reduction, of the AlN above the rods was determined by detailed weak beam (WB) electron microscopy studies and showed that the threading dislocation density (TDD) was greatly reduced, by approximately two orders of magnitude in the case for edge-type dislocations. In situ reflectance measurements during the overgrowth allowed for thickness coalescence to be estimated along with wafer curvature changes. The in situ measurements also confirmed that tensile strain built up at a much slower rate in the ELOG AlN layer compared to that of AlN prepared directly on sapphire