The Simulation And Research On MOS Controlled Thyristor (MCT)

This article introduces the development of power electronics and power semiconductor devices, which include three generations. The differences of the characteristics were listed and compared among the three generations. Thyristor, GTO and MCT were briefly presented. On the situation and development trend of domestic and foreign research, a brief presentation of status of MCT was made.Reasons of MCT’s turn-off failure were analyzed and summarized. After that maximum turn-off current was analyzed, and the factors which limit MCT maximum turn-off current were summarized. A new kind of structure of MCT is given and its characteristics were studied. The new structure includes a turn-off NMOS in the anode region, which can extract electrons stored in the N-drift region to promote turning off the MCT. Transient simulation results of conventional MCT and new MCT under inductive load were shown off, and the turn-off time was compared showing that the total turn-off time of the new MCT is only 66% of that of the conventional one. In the first stage, the turn-off time was cut down by 77% and at the second stage by 28%. A set of contrast were presented under the condition that for a given gate voltage, the conventional MCT couldn’t be turned off, while the novel one can be successfully turned off. It proves that compared with the conventional one, the maximum turn-off current is improved. Three-dimensional carrier distributions of N-drift region are illustrated at the time of turning on and turning off, which proves enhanced turn-off ability for the novel structure.A 600 V VDMOS termination was designed with field limiting ring technology. Several kinds of junction terminal technology were introduced and the relationship between breakdown voltage and the spacing of two neighboring rings was studied. The distances between each field limiting ring were determined, as well as with four rings. By simulation the final spacings were determined which were 5, 7, 8, 10.7 ?m, respectively. Besides that the effective terminal width is 125 ?m which is shorter than the other three papers by 34%, 30% and 21%, respectively, with field limiting ring technology and breakdown voltage of 600 V.