Dual-Drain GaN Magnetic Sensor Compatible With GaN RF Power Technology

This letter presents first–ever fabricated GaN split-current magnetic sensor device. This is the key technology needed to fully unlock the potential of GaN power technology. Device operation and key manufacturing steps are also presented. The measured relative current sensitivity is constant at 14 % T-1 for wide mT range of the magnetic field. The constant sensitivity of a fabricated sensor can be attributed to device’s 2DEG nature, i.e. its high electron concentration and mobility, and very small layer thickness

Analysis of GaN HEMTs Switching Transients Using Compact Model

The methodology to model GaN power HEMT switching transients at the circuit level is presented in this paper. A compact model to predict devices’ pulse switching characteristics and current collapse reliability issue has been developed. Parasitic RC subcircuits and a standard double-pulse switching tester to model intrinsic parasitic effects and to analyze power dissipation of GaN power HEMT are proposed and presented. Switching transient including gate-lag and drain-lag is predicted for ideal (without trap) and nonideal (with trap) devices. The results are validated by and compared to 2-D finite-element TCAD simulations. The developed methodology and compact model can successfully predict the dynamic behaviour of single and multiple power GaN HEMTs used for power electronics design

Safety and Stability of Structures with Semi-Rigid Connections of Members in Nodes

The structural design of a system in which connections of members are absolutely rigid or perfectly pinned has been thoroughly worked out in the existing literature. In real structures in general, and particularly in the precast ones, connection in joints may be partially rigid, which can have a significant impact on the change of stresses and strains in the structure, i.e. on the stability and security of the structure.Testing of engineering structures, i.e. conditions that must be met so that they remain in stable equilibrium position is of special importance. To determine the limit state of stability in use are experimental and analytical methods based on static, dynamic and energetic principles.This article presents the methods used to ensure technical safety and security, as well as additional safety conditioned by public and social reasons. The functional damage and fatigue are discussed, as well as the concept of the projected lifespan of the structure. Increased strength provides a higher degree of security, although many factors are variable

Manakins can produce iridescent and bright feather colours without melanosomes

Males of many species often use colourful and conspicuous ornaments to attract females. Among these, male manakins (family: Pipridae) provide classic examples of sexual selection favouring the evolution of bright and colourful plumage coloration. The highly iridescent feather colours of birds are most commonly produced by the periodic arrangement of melanin-containing organelles (melanosomes) within barbules. Melanin increases the saturation of iridescent colours seen from optimal viewing angles by absorbing back-scattered light; however, this may reduce the wide-angle brightness of these signals, contributing to a dark background appearance. We examined the nanostructure of four manakin species (Lepidothrix isidorei, L. iris, L. nattereri and L. coeruleocapilla) to identify how they produce their bright plumage colours. Feather barbs of all four species were characterized by dense and fibrous internal spongy matrices that likely increase scattering of light within the barb. The iridescent, yet pale or whitish colours of L. iris and L. nattereri feathers were produced not by periodically arranged melanosomes within barbules, but by periodic matrices of air and β-keratin within barbs. Lepidothrix iris crown feathers were able to produce a dazzling display of colours with small shifts in viewing geometry, likely because of a periodic nanostructure, a flattened barb morphology and disorder at a microstructural level. We hypothesize that iridescent plumage ornaments of male L. iris and L. nattereri are under selection to increase brightness or luminance across wide viewing angles, which may potentially increase their detectability by females during dynamic and fast-paced courtship displays in dim light environments

Manakins can produce iridescent and bright feather colours without melanosomes

Males of many species often use colourful and conspicuous ornaments to attract females. Among these, male manakins (family: Pipridae) provide classic examples of sexual selection favouring the evolution of bright and colourful plumage coloration. The highly iridescent feather colours of birds are most commonly produced by the periodic arrangement of melanin-containing organelles (melanosomes) within barbules. Melanin increases the saturation of iridescent colours seen from optimal viewing angles by absorbing back-scattered light; however, this may reduce the wide-angle brightness of these signals, contributing to a dark background appearance. We examined the nanostructure of four manakin species (Lepidothrix isidorei, L. iris, L. nattereri and L. coeruleocapilla) to identify how they produce their bright plumage colours. Feather barbs of all four species were characterized by dense and fibrous internal spongy matrices that likely increase scattering of light within the barb. The iridescent, yet pale or whitish colours of L. iris and L. nattereri feathers were produced not by periodically arranged melanosomes within barbules, but by periodic matrices of air and beta-keratin within barbs. Lepidothrix iris crown feathers were able to produce a dazzling display of colours with small shifts in viewing geometry, likely because of a periodic nanostructure, a flattened barb morphology and disorder at a microstructural level. We hypothesize that iridescent plumage ornaments of male L. iris and L. nattereri are under selection to increase brightness or luminance across wide viewing angles, which may potentially increase their detectability by females during dynamic and fast-paced courtship displays in dim light environments

High Sensitivity Dual-Gate Four-Terminal Magnetic Sensor Compatible with SOI FinFET Technology

This letter presents a unique device concept of split-current magnetic sensor that is fully compatible with SOI FinFET technology. The fabricated dual-gate four-terminal device brings a step change in SOI integrated sensor capabilities, its measured current related relative sensitivity is as high as 3400 % T-1 at 2 μA of total supply current, comparing to the sensitivity of 3%T-1 exhibited by commercially available silicon MagFETSs. The device’s very high sensitivity is attributed to its novel current conduction phenomena and the internal magnetic deflection enhancement loop demonstrated using 3D TCAD numerical simulations. This new magnetic sensor is a very promising candidate for the next generation of magnetic sensitive smart-power integrated circuits

TCAD Modelling of Magnetic Hall Effect Sensors

In this paper, a gallium nitride (GaN) magnetic Hall effect current sensor is simulated in 2D and 3D using the TCAD Sentaurus simulation toolbox. The model takes into account the piezoelectric polarization effect and the Shockley–Read–Hall (SRH) and Fermi–Dirac statistics for all simulations. The galvanic transport model of TCAD Sentaurus is used to model the Lorentz force and magnetic behaviour of the sensor. The current difference, total current, and sensitivity simulations are systematically calibrated against experimental data. The sensor is optimised using varying geometrical and biasing parameters for various ambient temperatures. This unintentionally doped ungated current sensor has enhanced sensitivity to 16.5 %T−1 when reducing the spacing between the drains to 1 μm and increasing the source to drain spacing to 76 μm. It is demonstrated that the sensitivity degrades at 448 K (S = 12 %T−1), 373 K (S = 14.1 %T−1) compared to 300 K (S = 16.5 %T−1). The simulation results demonstrate a high sensitivity of GaN sensors at elevated temperatures, outperforming silicon counterparts

Eavesdropping magpies respond to the number of heterospecifics giving alarm calls but not the number of species calling

Social information varies in its reliability and relevance, requiring individuals to use rules to avoid inappropriate responses to false information. A simple rule is to respond only when a certain number of individuals provide similar information. Although individuals within social groups can use such numerical rules to assess conspecific information and make consensus decisions, it is unknown whether individuals apply similar rules when assessing the value of heterospecific information. We consider the case of individuals eavesdropping on heterospecific alarm calls. Eavesdroppers may be particularly vulnerable to false alarms because of the large pool of potential callers and variability in the specific threats to which they call. Individuals might therefore value alarm calls more if they come from multiple callers or multiple species than from a single caller or a single species. We tested these predictions using field playback experiments on wild Australian magpies, Gymnorhina tibicen. Magpies responded more strongly to alarm calls coming from two callers versus one caller of the same heterospecific species. However, in contrast to our prediction, magpies responded similarly to alarm calls from two individuals of different species as they did to alarm calls from two individuals of the same species. We conclude that the number of calling individuals does affect response, probably because information from multiple callers is more reliable, but that the value or reliability of information from multiple species may depend on the types of alarm calls and combination of species involved.The work was funded by an Australian Research Council Discovery grant to R.D.M., A.N.R, and Esteban Fernandez- Juricic