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In this work, we investigate the time evolution of electrical degradation in AlGaN/GaN high electron mobility transistors after high temperature reverse bias(HTRB) stress. The threshold voltage shows a positive shift after stress, and then turns to negative shift. Comparing with the stressed and fresh devices, the fresh devices have more trap effect than the stressed which have stressed over 1000hours...
We have submitted the AlGaN/GaN High electron mobility transistors (HEMTs) to the high temperature reverse bias(HTRB) stress to assess their reliability for high voltage operations. The effects of HTRB stress as a function of the VDG and stress time on the DC parameters and trapping effects were investigated. The study was based on combined DC and pulsed characterization, transient measurement. It...
Temperature-dependent I-V characteristics are performed in this paper to investigate the trap states in AlGaN/GaN HEMTs. From temperature-dependent sub-threshold slope measurements conducted at 300K to 363K and 363K to 423K, two different trap densities are identified at AlGaN/GaN heterostructure interface with DitA and DitB of 1.08∼2.6×1012 eV•cm2 and 1.07∼1.44×1013 eV•cm−2 respectively. The trap...
This paper presents a control system of FPGA-based three-axis stepper motor with the hybrid stepper motor as the control object. The whole control system uses an external keyboard to control the start, stop, jog, acceleration, deceleration of the stepper motor, and realizes the detection of the motor speed through the rotary encoder, and the signal processed is displayed as the state of the motor...
In this work, we report on the effects of reverse gate bias step stress on the degradation of AlGaN/GaN high electron mobility transistors (HEMTs), consisting of a decrease in the drain current (IDS) and an increase in channel resistance (Ron). It was found that these degradations were accompanied with an anomalous decrease of gate current (Igoff). Interestingly, the nature of the degradation mentioned...
In this paper, the reliability in AlGaN/GaN HEMTs has been assessed by analyzing the spatial intensity distribution of electroluminescence (EL) detected by Photo Emission Microscope (PEM) during the OFF-state step-stress experiment. And it is found that a relationship between breakdown point and hot spots was confirmed. In addition, we report on the different of EL image before and after failure....
The application of denoising source separation (DSS) technology to the mechanical vibration signal processing provides a new technique of mechanical fault diagnosis. The DSS theory is investigated in this paper. The analog signals of the rotating machine are separated and the performance index and correlation coefficient of DSS are better than those of the joint approximate diagonalization of eigen-matrices...
With the rapid development of industrialization and urbanization, cities have become the centers to address the problem of climate change for China. Tianjin city plays an important role to boost the economy of North China according to the long-term development planning of China. Since a large amount of energy will be needed, the CO2 emission will be much more concerned. And it is essential for Tianjin...
The forming process of a warm extrusion punch of drilling bit shell is simulated by using contact analysis modules of ANSYS. Different friction coefficient and turning fillet radius is employed during its axis-symmetrical analysis. The results reveal the equivalent stress distribution and dangerous working regions on the punch under working condition. Furthermore, the optimal value 0.1 for friction...
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