Research On The Loss Characteristics Of Sic Power MOSFET

With the development of science and technology,silicon carbide power devices have attracted much attention,such as SiC power MOSFET.Compared with silicon-based power semiconductor,because of the low on-resistance,high temperature,high switching frequency and other characteristics,making SiC power MOSFET become the great candidates for high-voltage power switching applications.Realistic estimation of SiC power MOSFET switching losses is critical for predicting the maximum junction temperature and efficiency of power electronics circuits.Therefore,the correct calculation formula of switching loss is particularly important.The conventional ways of measuring switching losses lack the physical insight of the complicated switching process in power devices such as the SiC power MOSFET.This paper found a question about traditional formula of calculating switching losses by physical insights.Using a detailed finite element simulation model in SILVACO ATLAS,the difference of ICH and IDS in Si C power MOSFET is obtained.Then according to the experimental data,the real impact of output capacitor on switching losses is studied.Finally,we can obtain a more accurate formula of the switching losses.At present,the commercial semiconductor device simulation softwares have been developed for Si-based devices,and the effect of interface traps on the carriers in the channel of SiC power MOSFET can't been accurately reflected in these softwares.In this paper,an advanced mobility model is introduced in the commercial semiconductor device simulation software,and the effect of interface traps on the switching characteristics of SiC power MOSFET has been explored.Empty traps at the interface of SiO2/SiC can capture the carriers in the channel of SiC power MOSFET,at the same time,the occupied traps can scatter the carriers and decrease the mobility of carriers,so the traps have a severe effect on the switching characteristics of SiC power MOSFET.The results show that the higher density of interface trap delays the turn-on of SiC power MOSFET,but brings the device forward to turn-off in advance,and increases the on-state resistance,all these effects lead to the increasing of the device switching loss.The simulation in ATLAS and experimental show that the traditional switching loss calculation formula is not accurate.The 4H-SiC MOSFET model was established by using the semiconductor device simulation software ATLAS.The influence of interface traps on the characteristics of SiC devices was quantitatively studied by changing the interface trapdensity in the model.This will play an important role in the research and development of SiC power MOSFET in the future.