On the time-dependent transport mechanism between surface traps and the 2DEG in AlGaN/GaN devices

The physical mechanisms involved in the trapping and de-trapping processes associated to surface donor traps in GaN transistors are discussed in this work. The paper challenges the conventional transient techniques adopted for extrapolating the trap energy level via experiments and TCAD simulations. Transient TCAD simulations were employed to reproduce the time-dependent electrical behavior of a Metal-on-Insulator Field-Effect-Transistor (MISFET) and explain the influence of the electric field and energy barrier on the transient time associated to the trapping and de-trapping mechanisms of surface traps. The comparison between three test-structures and the relative variation of the trapping and de-trapping times with the bias and trap parameters leads to the suggestion of a proposed test-structure and bias configuration to accurately extrapolate the energy level of surface traps in GaN transistors

Reference and Definiteness

It has become increasingly clear since Longobardi (1994, 2003) that certain languages (e.g.Romance, but also Classical and Modern Greek, Bulgarian, Arabic (Fassi-Fehri 2003)…;henceforth 'strong D' languages) exhibit overt association of the referential content of nouns(proper names and referential generics) with D (either by overt N-to-D raising, e.g. of propernames, or by an arguably expletive article), others do not (e.g. English, but also probably therest of Germanic, Celtic…; 'weak D' languages). From a number of scattered observation itcan be suspected that a roughly analogous phenomenon arises with respect to anothersemantic property of DPs, namely definiteness: in certain constructions of some languages,but crucially not in the closely comparable constructions of others, the definite reading ofnominal arguments seems to depend on the overt association of some morphosyntacticmaterial with D (fronting to D° or SpecD)

The underlying unity of Reference and Quantification

The mapping of nominal arguments to semantic interpretation exhibits a certain amount ofintriguing empirical variation across languages; it has become increasingly clear, at least sinceLongobardi (1994), that a good deal of such polymorphy depends on a major parametricdivide, separating two types of languages: certain languages (e.g. Romance, but also Classicaland Modern Greek, Bulgarian, Arabic (Fassi-Fehri 2003)…; henceforth 'strong D' languages)exhibit overt association of nouns functioning as referential constants (proper names andreferential generics) with D (either by overt N-to-D raising, e.g. of proper names, or by anarguably expletive article), others do not (e.g. English, but also probably the rest of Germanic,Celtic…; 'weak D' languages)

Automorphism groups and new constructions of maximum additive rank metric codes with restrictions

Let $d, n \in \mathbb{Z}^+$ such that $1\leq d \leq n$. A $d$-code $\mathcal{C} \subset \mathbb{F}_q^{n \times n}$ is a subset of order $n$ square matrices with the property that for all pairs of distinct elements in $\mathcal{C}$, the rank of their difference is greater than or equal to $d$. A $d$-code with as many as possible elements is called a maximum $d$-code. The integer $d$ is also called the minimum distance of the code. When $d<n$, a classical example of such an object is the so-called generalized Gabidulin code. There exist several classes of maximum $d$-codes made up respectively of symmetric, alternating and hermitian matrices. In this article we focus on such examples. Precisely, we determine their automorphism groups and solve the equivalence issue for them. Finally, we exhibit a maximum symmetric $2$-code which is not equivalent to the one with same parameters known so far

Diamond power devices: state of the art, modelling, figures of merit and future perspective

Abstract: With its remarkable electro-thermal properties such as the highest known thermal conductivity (~22 W cm−1∙K−1 at RT of any material, high hole mobility (>2000 cm2 V−1 s−1), high critical electric field (>10 MV cm−1), and large band gap (5.47 eV), diamond has overwhelming advantages over silicon and other wide bandgap semiconductors (WBGs) for ultra-high-voltage and high-temperature (HT) applications (>3 kV and >450 K, respectively). However, despite their tremendous potential, fabricated devices based on this material have not yet delivered the expected high performance. The main reason behind this is the absence of shallow donor and acceptor species. The second reason is the lack of consistent physical models and design approaches specific to diamond-based devices that could significantly accelerate their development. The third reason is that the best performances of diamond devices are expected only when the highest electric field in reverse bias can be achieved, something that has not been widely obtained yet. In this context, HT operation and unique device structures based on the two-dimensional hole gas (2DHG) formation represent two alternatives that could alleviate the issue of the incomplete ionization of dopant species. Nevertheless, ultra-HT operations and device parallelization could result in severe thermal management issues and affect the overall stability and long-term reliability. In addition, problems connected to the reproducibility and long-term stability of 2DHG-based devices still need to be resolved. This review paper aims at addressing these issues by providing the power device research community with a detailed set of physical models, device designs and challenges associated with all the aspects of the diamond power device value chain, from the definition of figures of merit, the material growth and processing conditions, to packaging solutions and targeted applications. Finally, the paper will conclude with suggestions on how to design power converters with diamond devices and will provide the roadmap of diamond device development for power electronics