4H-SiC JBS diode with breakdown voltage higher than 4.5 kV, has been successfully fabricated on 4H-SiC wafers with epitaxial layer. In this paper we report the design, the fabrication, and the electrical characteristics of 4H-SiC JBS diode. Numerical simulations have been performed to select the doping level and thickness of the drift layer and the effectiveness of the edge termination technique. The epilayer properties of the N-type are 55 μm with a doping of 9×1014cm−3. The diodes were fabricated with a floating guard rings edge termination. The on-state voltage was 4V at JF=80 A/cm2

4H-SiC JBS diode with breakdown voltage higher than 6.5 kV has been successfully fabricated on 4H-SiC wafers with epitaxial layer. In this paper, the simulation, the fabrication, and the electrical characteristics of 4H-SiC JBS diode were reported. The drift layer thickness and doping are 55 μm and 9×1014cm3respectively. 60 floating guard rings edge were fabricated as termination. The on-state voltage was 4 V at JF= 7A.

High voltage 4H-SiC Ti Schottky junction barrier schottky (JBS) diode with breakdown voltage of 1700 V and forward current of 5 A has been fabricated. A low reverse leakage current below 3.8×10-5A/cm2at the bias voltage of -1700 V has been obtained. The forward on-state current was 5 A at VF= 1.7 V and 15.8 A at VF= 3 V. The active area is 1.5 mm × 1.5 mm. The turn-on voltage is about 0.9 V. The on-state resistance is 3.08 mΩ·cm2. The doping and thickness of the N-type drift layer and the device structure have been performed by numerical simulations. The SiC JBS devices have been fabricated and the processes were in detail. The die was assembled in a TO-220 package. The thickness of the N- epilayer is 17 µm, and the doping concentration is 3.2 × 1015cm−3. The number of floating guard p-rings was chosen to be 25, the distance between the rings was chosen to be 0.7 µm ~ 1.3 µm and the width of the p-rings is 2.5 µm. We use the PECVD SixNy/SiO2as the passivation dielectric and a non photosensitive polyamide as the passivation in the end. The reverse recovery current Irwas 1.26A and the reverse recovery time Trrwas 26ns when the diode was switched from 5A forward current to a reverse voltage of 700V. The reverse recovery electric charge Qrrof 16nC was obtained.

Cost control is an important measure to improve economic benefit of enterprises, while the theory of value engineering (VE) is the best method to coordinate improving product performance with reducing the cost of production. It realizes the improvement of the value of product and economic benefit, and achieving the purpose of optimizing the cost structure. The theory of value engineering is innovatively applied to the study of cost control of the marine diesel, the function analysis system technique graphical method (FAST) is used to analyze the function of the marine diesel to screen out 16 key components which are the research elements of Value Engineer. The comprehensivefunction proportion analysis and cost analysis method are used to analyze their value and determine the components which need to be improved. At last, this paper gives out the enforceable improving scheme.

A graphene-based flexible filter was obtained via one-step laser heating of a polyimide film. The key parameters of a laser have been confirmed by comparing simulated results and experimental data. High-frequency components of input signals were filtered out effectively for different waveforms, such as sine, rectangular, triangle and pulse waveforms. In order to study filtering performance, this paper focused on amplitude frequency curve, phase frequency curve, transient response and mechanical stability. The phase frequency curve is linear distribution, indicating that it is convenient to control phase shift. The mechanical stability of the device remains good even after 5000 bends, which is unreported in previous work. This paper demonstrated that a graphene-based flexible filter prepared by one-step laser heating has excellent performance and opens new way of thinking about flexible electronics in the future.