1,721,001 research outputs found
Metal/semiconductor contacts to silicon carbide: Physics and technology
No full textThe physics and technology of metal/semiconductor interfaces are key-points in the development of silicon carbide (SiC) based devices. Although in the last decade, the metal to 4HSiC contacts, either Ohmic or Schottky type, have been extensively investigated with important achievements, these remain even now an intriguing topic since metal contacts are fundamental bricks of all electronic devices. Hence, their comprehension is at the base of the improvement of the performances of simple devices and complex systems. In this context, this paper aims to highlight some relevant aspects related to metal/semiconductor contacts to SiC, both on n-type and p-type, with an emphasis on the role of the barrier and on the carrier transport mechanisms at the interfaces.</p
Properties of Al2O3 thin films deposited on 4H-SiC by reactive ion sputtering
No full textIn this work, the electrical properties of Al2O3 films deposited by reactive ion sputtering were investigated by means of morphological, chemical and electrical characterizations. We observe that the electron trapping affecting the insulating layer is mitigated after a rapid thermal annealing (RTA) treatment. The RTA improved also the permittivity (up to 6ε0), although the negative fixed charge remains in the order of 1012 cm−2. However, the temperature dependent electrical investigation of the metal-oxide-semiconductor (MOS) capacitors demonstrates that the room temperature Fowler-Nordheim electron barrier height of 2.37 eV lies between the values expected for SiO2/4H-SiC and Al2O3/4H-SiC systems
A novel experiment approach to ohmic contact formation on p-doped SiC
No full textIn this work, the fabrication of a novel configuration for an ohmic contact on p-doped SiC substrate, employing laser treatment instead of the conventional oven treatment, is analyzed. Test patterns made by Ti rectangular contacts on p-SiC were fabricated. The overall structure is treated with an excimer laser, employing different energy densities and number of shots. In particular, the laser energy density ranges from 1.0 J/cm2 to 3.8 J/cm2 and the number of shots from 1 to 10. The analysis shows that the system begins to exhibit an ohmic behavior when exposed to laser energy densities of 3.6 J/cm2 and above. Also, the number of shots influences the electrical behavior, with higher values leading to losing the linearity in the I-V curves. The best performance, characterized by the lowest resistivity value, is observed with an energy density value of 3.8 J/cm2 and 1 laser shot applied. Under these conditions, the resistivity value is 1.4x10-2 Ωcm, or in terms of specific resistivity 7x10-5 Ωcm2, the contact resistance is 152 Ω and the sheet resistance is 656 Ω/sq. This work enables the achievement of an ohmic contact between Titanium and p doped SiC, overcoming the challenge of using high temperature oven treatment
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Feature Papers in Electronic Materials Section (Volume 2)—15th Anniversary of Materials
No full textThis reprint, entitled "Feature Papers in Electronic Materials Section – Volume 2", is a collection of selected papers recently published in the MDPI journal Materials, focusing on the latest advances in electronic materials and devices in different fields (e.g., power and high-frequency electronics, optoelectronic devices, sensors, etc.). The first part of the volume is dedicated to the most popular wide-bandgap semiconductors (WBG), i.e., silicon carbide (SiC) and gallium nitride (GaN), focusing on specific materials and device technology issues, as well as new applications. The second part of the reprint is a miscellaneous collection of other electronic materials for various applications, including graphene, and other materials for high-frequency devices, solar cells, and sensors
Ammonothermal Crystal Growth of Functional Nitrides for Semiconductor Devices: Status and Potential
Full text linkThe state-of-the-art ammonothermal method for the growth of nitrides is reviewed here, with an emphasis on binary and ternary nitrides beyond GaN. A wide range of relevant aspects are covered, from fundamental autoclave technology, to reactivity and solubility of elements, to synthesized crystalline nitride materials and their properties. Initially, the potential of emerging and novel nitrides is discussed, motivating their synthesis in single crystal form. This is followed by a summary of our current understanding of the reactivity/solubility of species and the state-of-the-art single crystal synthesis for GaN, AlN, AlGaN, BN, InN, and, more generally, ternary and higher order nitrides. Investigation of the synthesized materials is presented, with a focus on point defects (impurities, native defects including hydrogenated vacancies) based on GaN and potential pathways for their mitigation or circumvention for achieving a wide range of controllable functional and structural material properties. Lastly, recent developments in autoclave technology are reviewed, based on GaN, with a focus on advances in development of in situ technologies, including in situ temperature measurements, optical absorption via UV/Vis spectroscopy, imaging of the solution and crystals via optical (visible, X-ray), along with use of X-ray computed tomography and diffraction. While time intensive to develop, these technologies are now capable of offering unprecedented insight into the autoclave and, hence, facilitating the rapid exploration of novel nitride synthesis using the ammonothermal method.This research was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—512083685 and Lehigh University New Faculty Start-up Funds.Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)Lehigh University New Faculty Start-up Fund
Simulation-Guided Analysis towards Trench Depth Optimization for Enhanced Flexibility in Stretch-Free, Shape-Induced Interconnects for Flexible Electronics
Full text linkIn this paper, we present an optimization of the planar manufacturing scheme for stretch-free, shape-induced metal interconnects to simplify fabrication with the aim of maximizing the flexibility in a structure regarding stress and strain. The formation of trenches between silicon islands is actively used in the lithographic process to create arc shape structures by spin coating resists into the trenches. The resulting resist form is used as a template for the metal lines, which are structured on top. Because this arc shape is beneficial for the flexibility of these bridges. The trench depth as a key parameter for the stress distribution is investigated by applying numerical simulations. The simulated results show that the increase in penetration depth of the metal bridge into the trench increases the tensile load which is converted into a shear force Q(x), that usually leads to increased strains the structure can generate. For the fabrication, the filling of the trenches with resists is optimized by varying the spin speed. Compared to theoretical resistance, the current–voltage measurements of the metal bridges show a similar behavior and almost every structural variation is capable of functioning as a flexible electrical interconnect in a complete island-bridge array.This research received no external funding
- …
