The SuperJunction MOS-controlled thyristor (SJ-MCT) with low power loss for high-power switching applications

Abstract

In this paper, a novel MOS controlled-thyristor (MCT) that employs the SuperJunction concept (SJ-MCT) has been investigated, for the first time. The SJ-MCT offers significant improvement in the on-state voltage drop (V on ) and turn-off switching loss (E off ) compared with the state-of-the-art conventional MCT. In the on-state, due to the p-type pillar of the SJ structure in the SJ-MCT drift region, an effective collector area of the lower PNP transistor in MCT is enlarged, which results in higher conductivity modulation and then lower V on . For the turn-off of SJ-MCT, the introduction of SJ structure in the drift region is helpful to extract the minority carriers stored in the drift region during the forward conduction, which leads to lower turn-off time and then lower E off . In addition, the SuperJunction structure can deliver charge balance in the drift region results in smaller drift lengths and higher doping levels, which also contributes to better on-state/switching trade-off. At the condition of anode current density of 400 A/cm 2 , the V on and E off of SJ-MCT is 1.12 V and 6.7mJ, compared with 1.34V and 11 mJ for MCT, respectively. IntroductionHigh-power semiconductor devices are critical components in a wide variety of power electronics applications like motor control in traction system. Desired device characteristics for such applications are low on-state voltage drop, high current and high blocking capability, simple gate drive and low switching loss [1][2][3]. The IGBT offers excellent characteristics for medium-power applications, while it has been found that this device has a high V on at a larger current density when designed for the high-power applications [4][5]. As an alternative, MOS controlled-thyristor (MCT) has been studied for the high-power applications because of its simple gate control, high blocking capability and low V on [2,3,6]. However, MCT has a longer turn-off time as compared with IGBT due to its larger amounts of minority carriers stored in the drift region, which leading to a higher E off [7]. In this paper, we propose and describe a new device, the SuperJunction MOS controlled thyristor (SJ-MCT) which not only improve its V on but also reduces its E off without compromising its current