Optimum built-in barrier height utilizing an extended concept of impedance matching
Schottky-barrier height optimization for high-frequency usage is analytically discussed with an extended concept of impedance matching. The optimum value of 0.3 eV is almost a universal constant under various operating conditions, and agrees well with the previous prediction obtained by large signal simulation and InxGa1-xAs experiments.
Schottky Barrier Diode Optimization for a Low Voltage Power Converter
Optimun barrier height and impurity concentration for a power Schottky diode for maximizing rectifying efficiency are theoretically derived. For a low output voltage, 1.5 ~ 2 V as a DC-DC converter, the barrier height has an optimum value of about 17 times the thermal voltage and the impurity concentration has approximately 1 × 1016 cm-3, for n-type silicon. Schottky diodes with some kinds of barrier metals, such as titanium, hafnium and zirconium were fabricated and applied to a forward mode 2 V 50 A DC-DC converter. Power loss and efficiency were investigated in comparison with control molybdenum diodes. Titanium and hafnium diodes reduced the power loss from 49 W to 37 W for main circuit total loss, which improved the efficiency from 67% to 73%, at package surface temperatures below 60°C. These diodes show better efficiency up to 85°C, compared with molybdenum diodes. Smaller heat sinks or cooling fins can be used because of those low loss characteristics.
Application of infrared camera to bituminous concrete pavements: measuring vehicle
Infrared thermography (IR) has been used for decades in certain fields. However, the technological level of advancement of measuring devices has not been sufficient for some applications. Over the recent years, good quality thermal cameras with high resolution and very high thermal sensitivity have started to appear on the market. The development in the field of measuring technologies allowed the use of infrared thermography in new fields and for larger number of users. This article describes the research in progress in Transport Research Centre with a focus on the use of infrared thermography for diagnostics of bituminous road pavements. A measuring vehicle, equipped with a thermal camera, digital camera and GPS sensor, was designed for the diagnostics of pavements. New, highly sensitive, thermal cameras allow to measure very small temperature differences from the moving vehicle. This study shows the potential of a high-speed inspection without lane closures while using IR thermography.