| It's an important task to improve the whole performance of power device, mainly including breakdown voltage, specific on-resistance and switching speed, to approach the ideal situation, which means infinite value of resistance while in its off-state and zero while in its on-state, furthermore it never breakdowns and needs no time to switch. Unfortunately, the relationship among the three characteristics limits the improvement of whole performance.It's convenient to control MOSFET and IGBT since they are field-controlled devices. Although MOSFET switches fast, it can't sustain high voltage while maintains low specific on-resistance because it conducts current only by majority carriers. IGBT has excellent performance of both breakdown voltage and specific on-resistance. But the slow turn-off speed is always the problem when it is applied, since the removal of the carriers mainly depends on the recombination.The purpose of this thesis is to improve the whole performance by some new ideas and optimization based on the thorough review of the development of the power device.The main tasks of this thesis are: obtaining a general situation of the development of the power device; simple analysis of the SOI device; the optimization of the interdigitated Composite Buffer structure; realizing three resolutions of simply controlling the double-gated IGBT; accurate analytical analysis of the thin-film SOI-LDMOS with resistive field plate. The innovative ones are as follows.1. The optimization of the interdigitated Composite Buffer structure.The results of the detail analysis on the Composite Buffer structure have been published in the patent file applied by Chen X. B. in 1993[ChenX.B., 1993], and more systemic theories have been presented thereafter[Chen X.B., 1998, 2000, 2001, 2002], based on which the optimization of one cell form - interdigated CB is accomplished in this thesis. First, the optimum relationship between the breakdown voltage and the specific on-resistance is obtained based on the electrical field analysis. Then, three resolutions are presented to achieve the most optimum relationship, which shows good agreement with the numerical results.2. The realization of a high speed, low power dissipation, low-side device of the half-bridge output section.During the research of the electrical lamp ballast, we achieved an idea according to the characteristics of the driving signals of the half-bridge output section, which is that introducing a double-gated IGBT into the output section acting as the low-side device, and whether anode-short or not is controlled by the high-side driving signal. Then the low-side device performs just like a normal IGBT while in its on-state, but turns off in the anode-short mode, which leads to low forward voltage drop and fast turning off without adding more controlling circuits. According to the simulation results, the advantage of improving the switching speed is obvious. Moreover, this idea can be applied in the situation of capacitive load or inductive load. Obviously, the sustaining voltage can also be increased since the anode-short structure makes the breakdown performance of the IGBT close to a normal PN junction.3. A high speed IGBT based on dynamic controlled anode-shortIGBT with high switching speed is described based on the dynamic controlled anode-short, which incorporates a normally-on p-MOSFET controlled by the anode voltage indirectly. This device works just as normal when it's in on-state, since the channel of the p-MOSFET is kept off. During the course of turning off, the channel of the p-MOSFET will prevent the injection of minorities and introduce an extra access for the carriers to flow to the anode directly, which makes the IGBT reach its off-state in a shorter time. The simulation results prove that the new structure can reduce the turn-off time compared with the normal one under the same on-state performance and higher breakdown voltage. And can operate under the situation of parameters which are not in accordance with the design va...
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