Thermo-Mechanical Simulation of Self-Heating of a High-Power Diode Made of Ti3SiC2 (MAX) Phase-on-4H-SiC Substrate

Abstract

The fact that traditional semiconductors have almost reached their performance limits in high power applications, is leading to failure in high power devices. This failure results from self-heating effects, leading to higher temperature and a breakdown of the electrical contact. The good thermal and mechanical properties of 4H-SiC and Ti3SiC2 and their good performance at high temperatures make them good candidates for high power applications. In order to improve the performance of electrical contacts, a thermo-mechanical simulation was carried out using the finite element method to study the self-heating effects in a high power PN diode made of a 4H-SiC substrate with a Ti3SiC2 electrical contact and Al3Ti metallization. The three-dimensional model took into account the temperature dependency of several thermal and mechanical properties of the different materials to improve calculation accuracy. To simulate the self-heating, the power loss in the diode was calculated from the corresponding direct I-V characteristic. In addition, the interfacial thermal resistances (ITR) between the different layers were varied and studied in the thermo-mechanical investigation, in sequence to determine their effects on the heat dissipation and the resulting stresses in the model. The results show that for realistic ITR values, the ITR barely affects heat diffusion mechanical stresses of the model. Whereas, ITR may cause serious problem to the functionality and the efficiency of some electronic components. On the other hand, extremely large ITR leads to a decrease in the thermal stress in the diode. Good control on the ITR may help to improve the performance of high-power devices in the future, in addition to providing more efficient electrical contacts.