Atomic resolution interface structure and vertical current injection in highly uniform MoS2MoS_{2} heterojunctions with bulk GaN

The integration of two-dimensional $MoS_{2}$ with $GaN$ recently attracted significant interest for future electronic/optoelectronic applications. However, the reported studies have been mainly carried out using heteroepitaxial $GaN$ templates on sapphire substrates, whereas the growth of $MoS_{2}$ on low-dislocation-density bulk GaN can be strategic for the realization of truly vertical devices. In this paper, we report the growth of ultrathin $MoS_{2}$ films, mostly composed by single-layers ($1L$), onto homoepitaxial $n-GaN$ on $n^{+}$ bulk substrates by sulfurization of a pre-deposited $MoO_{x}$ film. Highly uniform and conformal coverage of the $GaN$ surface was demonstrated by atomic force microscopy, while very low tensile strain (0.05%) and a significant $p^{+}$-type doping ($4.5 \times 10^{12} cm^{-2}$) of $1L-MoS_{2}$ was evaluated by Raman mapping. Atomic resolution structural and compositional analyses by aberration-corrected electron microscopy revealed a nearly-ideal van der Waals interface between $MoS_{2}$ and the $Ga$-terminated $GaN$ crystal, where only the topmost $Ga$ atoms are affected by oxidation. Furthermore, the relevant lattice parameters of the $MoS_{2}/GaN$ heterojunction, such as the van der Waals gap, were measured with high precision. Finally, the vertical current injection across this 2D/3D heterojunction has been investigated by nanoscale current-voltage analyses performed by conductive atomic force microscopy, showing a rectifying behavior with an average turn-on voltage $V_{on}=1.7 V$ under forward bias, consistent with the expected band alignment at the interface between $p^{+}$ doped $1L-MoS_{2}$ and $n-GaN$.Comment: 21 pages, 6 figure

Integrating Entrepreneurship into the Design Classroom: Case Studies from the Developing World

© 2017, Springer Science+Business Media, LLC. Developing countries are more and more committed to building a knowledge-based economy as a means to diversify from their current resource-based economy. The current focus of many governments is on technology with real insights on creative economy and arts. In this context, universities are seen as a key partner of the government. This article presents the results of two innovative case studies of professors working in the College of Art and Design collaborating with a professor in the College of Business to integrate the concepts of entrepreneurship into their interior design courses. This was done through designing space for entrepreneurial projects and by the students acting as entrepreneurs themselves with an external client. This dual model of training combines (1) learning processes about the habits and the needs of entrepreneurs and (2) learning by acting as an entrepreneur. Such methods demonstrate the role of universities to provide a proper theoretical background for students and to foster entrepreneurial behaviors through arts entrepreneurship education. Furthermore, the central role of professors to introduce innovative teaching methods to combine entrepreneurship and the creative economy into non-business courses is an important finding in these case studies

Evaluation of shallow landslide-triggering scenarios through a physically based approach: an example of application in the southern Messina area (northeastern Sicily, Italy)

Rainfall-induced shallow landslides are a widespread phenomenon that frequently causes substantial damage to property, as well as numerous casualties. In recent~years a wide range of physically based models have been developed to analyze the triggering process of these events. Specifically, in this paper we propose an approach for the evaluation of different shallow landslide-triggering scenarios by means of the TRIGRS (transient rainfall infiltration and grid-based slope stability) numerical model. For the validation of the model, a back analysis of the landslide event that occurred in the study area (located SW of Messina, northeastern Sicily, Italy) on 1 October 2009 was performed, by using different methods and techniques for the definition of the input parameters. After evaluating the reliability of the model through comparison with the 2009 landslide inventory, different triggering scenarios were defined using rainfall values derived from the rainfall probability curves, reconstructed on the basis of daily and hourly historical rainfall data. The results emphasize how these phenomena are likely to occur in the area, given that even short-duration (1–3 h) rainfall events with a relatively low return period (e.g., 10–20~years) can trigger numerous slope failures. Furthermore, for the same rainfall amount, the daily simulations underestimate the instability conditions. The high susceptibility of this area to shallow landslides is testified by the high number of landslide/flood events that have occurred in the past and are summarized in this paper by means of archival research. Considering the main features of the proposed approach, the authors suggest that this methodology could be applied to different areas, even for the development of landslide early warning systems

Validation of a shallow landslide susceptibility analysis through a real case study. An example of application in Rome (Italy)

In the last years, statistically based models (such as Logistic Regression) have been frequently used for evaluating the probability of landslide occurrence over large areas. In the case of Rome, over the years, more than 348 landslides have been recorded throughout the city. For this reason, in this study, we implemented and evaluated three main validation criteria of logistic regression to assess the rainfall-induced landslide susceptibility in a specific area of the city of Rome. Through the evaluation of the predictive performances, the best model has been identified and the results were also compared with those obtained in similar case studies