Conversion pathways of primary defects by annealing in proton-irradiated n-type 4H-SiC

The development of defect populations after proton irradiation of n-type 4H-SiC and subsequent annealing experiments is studied by means of deep level transient (DLTS) and photoluminescence (PL) spectroscopy. A comprehensive model is suggested describing the evolution and interconversion of irradiation-induced point defects during annealing below 1000{\deg}C. The model proposes the EH4 and EH5 traps frequently found by DLTS to originate from the (+/0) charge transition level belonging to different configurations of the carbon antisite-carbon vacancy (CAV) complex. Furthermore, we show that the transformation channel between the silicon vacancy (VSi) and CAV is effectively blocked under n-type conditions, but becomes available in samples where the Fermi level has moved towards the center of the band gap due to irradiation-induced donor compensation. The annealing of VSi and the carbon vacancy (VC) is shown to be dominated by recombination with residual self-interstitials at temperatures of up to 400{\deg}C. Going to higher temperatures, a decay of the CAV pair density is reported which is closely correlated to a renewed increase of VC concentration. A conceivable explanation for this process is the dissociation of the CAV pair into separate carbon anitisites and VC defects. Lastly, the presented data supports the claim that the removal of free carriers in irradiated SiC is due to introduced compensating defects and not passivation of shallow nitrogen donors

Changing vacancy balance in ZnO by tuning synthesis between zinc/oxygen lean conditions

The nature of intrinsic defects in ZnO films grown by metal organic vapor phase epitaxy was studied by positron annihilation and photoluminescence spectroscopy techniques. The supply of Zn and O during the film synthesis was varied by applying different growth temperatures (325–485 °C), affecting decomposition of the metal organic precursors. The microscopic identification of vacancy complexes was derived from a systematic variation in the defect balance in accordance with Zn/O supply trends.Peer reviewe

Testing ZnO based photoanodes for PEC applications

AbstractWe report on multi layered ZnCdO photoanode structures synthesized on c-A12O3 substrates using metal organic vapor phase epitaxy and covered with a thin TiO2 protective film using atomic layer deposition and pulsed laser deposition techniques. Structural, optical and photoelectrochemical properties of the multilayers were investigated systematically in connection with their potential application in the photolysis of water. X-ray diffraction and Rutherford backscattering techniques confirmed staggered arrangement and graded Cd content of the multilayers. Temperature-dependant photoluminescence revealed excitonic nature of a broad emission band representing combined band-edge emissions from the individual layers. The photocurrent was found to increase with decreasing thickness of the TiO2 protective layer

Effect of substrate proximity on luminescence yield from Si nanocrystals

The influence of the proximity of a high refractive index substrate on the luminescence of Si nanocrystals was investigated by time-integrated and time-resolved photoluminescence. The luminescence yield was found to be ∼2.5 times larger for emitters distanced from the substrate compared to those in proximity with the substrate, while luminescence decay measurements revealed only a slight increase in the luminescence lifetime (∼15%). Results are discussed in terms of local density of optical modes surrounding a pointlike light emitter with important implications for the collection efficiency of luminescence and the estimation of internal quantum efficiency for a quantum dot.Support for this work was provided by the Swedish Research Council VR and the Australian Research Council ARC

Cross-Sectional Carrier Lifetime Profiling and Deep Level Monitoring in Silicon Carbide Films Exhibiting Variable Carbon Vacancy Concentrations

The carrier lifetime control over 150 μm thick 4H-SiC epitaxial layers via thermal generation and annihilation of carbon vacancy (VC) related Z1/2 lifetime killer sites is reported. The defect developments upon typical SiC processing steps, such as high- and moderate-temperature anneals in the presence of a carbon cap, are monitored by combining electrical characterization techniques capable of VC depth-profiling, capacitance–voltage (CV) and deep-level transient spectroscopy (DLTS), with a novel all-optical approach of cross-sectional carrier lifetime profiling across 4H-SiC epilayer/substrate based on imaging time-resolved photoluminescence (TRPL) spectroscopy in orthogonal pump-probe geometry, which readily exposes in-depth efficacy of defect reduction and surface recombination effects. The lifetime control is realized by initial high-temperature treatment (1800 °C) to increase VC concentration to ≈1013 cm−3 level followed by a moderate-temperature (1500 °C) post-annealing of variable duration under C-rich thermodynamic equilibrium conditions. The post-annealing carried out for 5 h in effect eliminates VC throughout the entire ultra-thick epilayer. The reduction of VC-related Z1/2 sites is proven by a significant lifetime increase from 0.8 to 2.5 μs. The upper limit of lifetimes in terms of carrier surface leakage and the presence of other nonradiative recombination centers besides Z1/2, possibly related to residual impurities such as boron are discussed.publishedVersio

Zinc vacancy and oxygen interstitial in ZnO revealed by sequential annealing and electron irradiation

By combining results from positron annihilation and photoluminescence spectroscopy with data from Hall effect measurements, the characteristic deep level emission centered at ∼1.75 eV and exhibiting an activation energy of thermal quenching of 11.5 meV is associated with the zinc vacancy. Further, a strong indication that oxygen interstitials act as a dominating acceptor is derived from the analysis of charge carrier losses induced by electron irradiation with variable energy below and above the threshold for Zn-atom displacement. We also demonstrate that the commonly observed green emission is related to an extrinsic acceptorlike impurity, which may be readily passivated by oxygen vacancies.Peer reviewe

European Report on Prisoner Reintegration through Entrepreneurship and Psychology

It has been well documented that reintegration into the workforce is a key factor in reducing recidivism amongst people with a criminal record. However, mainstream employment poses a challenge for many individuals with criminal histories who experience discrimination from prospective employers. Entrepreneurship or self-employment offers an alternative pathway into the labour market but it is not widely promoted as a viable career option. In recent years, in-prison entrepreneurship education programmes (particularly in the USA) have grown in prominence to offer participants another option in terms of future labour market activation. Despite the recorded success of these initiatives, the adoption of such programmes within Europe is not widespread. The aim of this report is to provide evidence-based analysis and recommendations for the piloting of an e-learning entrepreneurship education programme developed under PREP (Prisoner Reintegration through Entrepreneurship and Psychology) which is an EU Erasmus+ funded project. The report covers the criminal justice systems across three national contexts – Ireland, Germany and Romania. The data for the findings and recommendations derive from a literature review of the key academic fields and country-level interviews conducted with justice-impacted individuals and key informants across the criminal justice systems.ERASMUS+ Strategic Partnership

DIGITAL EDUCATION : TO TACKLE CLIMATE CHANGE

To achieve long-term sustainability individuals, groups, and organizations need to mitigate climate change and adapt to the new environmental scenarios. Indeed, climate change is a process that cannot be ignored in any way any longer. Not only it is happening everywhere, and the effects are more noticeable every year, but it has also been happening for decades with an impact on every ecosystem of the planet. This means that climate change is a fundamental issue that affects every person, group, and organization. Professionally, we need as much expertise as we can gather. More practitioners are needed with experience in every field to help mitigate climate change as much as possible while facilitating rapid adaptation to a progressively damaging climate change. Climate change is caused by humans and human behavior, even if some issues seem technological and environmental problems, the origin is still human behavior. Therefore, there is a critical need for being able to count on behavioral experts that contribute to explaining current behaviors. Additionally, behavior change experts who are able to motivate individuals, groups, and organizations to engage in mitigation and adaptation behaviors are equally necessary. To achieve this, a more comprehensive range of educational opportunities is needed. This education must be included in vocational training and applied science universities. However, nothing will have an impact as far-reaching as education about climate change for students during their bachelor and master programs. The capacity of highly trained professionals with behavioral change expertise can have a trickling-down effect that will benefit the whole world. Because of how crucial education in climate change is, an urgent need is currently a pressing matter to provide specialized education on how to understand and improve the sustainability behavior of people, groups, and organizations. This need to increase both the amount and quality of sustainability-related education is met with an insufficient amount of education resources being offered. Creating new courses or even programs on this topic is not a realistic possibility for many institutions. In some cases, the development of new content might not be feasible due to local difficulties, and in other cases, climate change might not be a preference whatsoever. Therefore, it is crucial to offer alternatives to institutions that due to factors such as lack of local expertise, different agendas, or the difficulties linked to generating new content cannot offer education on climate change and behavior themselves. This education alternative should be easy to implement and adapt to the specific programs. The most straightforward contribution to facilitating education in climate change at bachelor and master levels is offering online courses that can be imported. Additionally, to maximize the reach of these courses, they should include content that can be learned in a self-guided manner. The PSYCLIC project offers the latest content about climate change and human behavior. This material will be available to be directly imported digitally at any university program. Additionally, it has a modular structure that is self-guided by default. However, the education resource that the PSYCLIC project offers will not make a meaningful impact unless the target community (i.e., institutions that could offer education on the topic of climate change and behavior but do not do so) is eager to use the education resources that the project will offer. To understand if the profile of scholars that the PSYCLIC project has as the target are ready and kin on using what the project will offer, we reached other colleagues to explore the demands and barriers for ready to use digital education material on climate change and behavior.ERASMUS+ / Projektname: Psychology and Climate Change - Digital Education / Projekt Akronym: PSYCLI