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In this work, the high temperature (up to 375°C) dynamic characteristics of 1.2kV SiC VDMOS, including the gate charge, the switching and the body diode reverse recovery characteristics, are measured and analyzed in detail. The experiments show that, with the increase of temperature, the Miller plateau declines, the reverse recovery charge rises, the turn-on time decreases and the turn-off time increases respectively. Moreover, the thermal failure mechanism of the device during reverse recovery operation is presented in this paper.

The performances of 4H-SiC power Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) with defects induced by cosmic radiations are studied in this paper. By SRIM and SILVACO T-CAD simulations, the radiation effects on the electrical parameters of the device are observed. The results indicate that the radiations from different directions induce defects in different regions of the device. The defects under the P+ source make the drain-source on-state resistance (Rdson) increase obviously. The defects in the drift region can result in little increase of the drain-source breakdown voltage (BV).

In this work, a useful interfacial damage extraction method for SiC power MOSFETs based on the C-V characteristics is proposed. According to the five different interface situations of the channel region and the JFET region, the Cg-Vg curve can be divided into five relatively independent parts. It demonstrates that the charges injected into the oxide of channel region will lead to an opposite shift in part 11 while the charges injected into the JFET region will result in the shifts in part 111 and IV. Through this way, the location of the charges injected in to the SiO 2 /SiC interface can be distinguished. The correctness of the method is proved by a UIS-stressed SiC power MOSFET. Moreover, the density of the charges injected into the interface oxide can be calculated by the amplitude of the shift in the Cg-Vg characteristic.

An onion-like carbon material was prepared from candle soot, and its tribological properties as an additive were investigated in water. The material assumed a spherical shape with a layered nanostructure based on high-resolution transmission electron microscopic analysis and had considerable sp2 hybrid carbon as revealed by Raman spectroscopy. The tribological properties were determined on an optimal SRV-IV oscillating reciprocating friction and wear tester. The results indicate that these candle soots as additives are able to effectively reduce both the friction and wear of sliding pairs in water. In addition, the chemical reactivity, physical stability, surface charge, and size of candle soot had a key impact on their lubrication properties. Based on our characterization of the wear scars by scanning electron microscopy and in situ Raman spectroscopy, we suggest a rolling and sliding lubrication mechanism.

This study provided a new configuration of the 180-deg round turned channel with a perforated divider, as well as numerically investigated the effect of perforations, including the diameter of perforation and the angel of perforation, on the fluid flow and heat transfer. The numerical results appeared in good agreement with previous experimental data under the same operating conditions. The results indicated that large size and positive angle of perforation changed the fluid flow pattern and the local Nusselt-number distribution fundamentally. It is noteworthy that a more uniform distribution of Nusselt-number was achieved by increasing the diameter of perforation.

Combining recent condition and trend of product digital design, this paper analyzes the main ideal and process of modern product design, and dissertates the aided effects of CAD/CAM in modern product design. This paper demonstrates detailedly the practicability to realize whole process of product design efficiently by composing existing software in CAD/CAM. Based on these, this paper brings forward viable project to product digital design based on design process. Implementation of this project can heighten design efficiency and shorten design cycle.

In this work, the Hot-Carrier-Induced (HCI) degradation mechanism of the 30 V shallow trench isolation (STI) n-type lateral DMOS (nLDMOS) with two-step-oxide process applied in high side application (called as HS-nLDMOS) is investigated. It implies that the Ron, sp (on-resistance measured under high side condition) suffers from more damage impact than Ron, ls (on-resistance measured under low side condition). Moreover, a shift of the worst stress condition from the maximum substrate current stress condition (Isubmax) to the maximum gate voltage stress condition (Vgmax) is observed when the HS-nLDMOS is evaluated with Ron, hs instead of Ron, ls. Hence our investigation suggests estimating the degradation of HS-nLDMOS by Ron, hs under Vgmax stress condition in order to evaluate the exact life of the device.

With the increase of output power and temperature, traditional package technology for AC-DC chips, such as dual inline-pin (DIP) package, can no longer be used in high-power density adapters due to the poor heat dissipation characteristic. In order to solve the problem, a novel package solution for AC-DC chips applied in high output power situations is introduced in this paper. The AC-DC chip is TO-220-5L packaged in which the control IC is stacked on the power MOSFET. The thermal simulations of both the original DIP package and the improved stack TO-220-5L package are presented as a comparison. The junction temperatures of devices in the proposed TO-220-5L package turn out to be much lower than that in DIP package. A steady state thermal test is also made on an adapter with 36W output power to verify the practicability of the novel stack packaged AC-DC chip. As a result, a steady temperature of 94.8°C implies that the improved package solution can solve the over-heat issue and work as normal in such high-power density adapters.