Early diagnosis in power semiconductors: MOSFET, IGBT, emerging materials (SiC and GaNs)

The reliability of a power converter depends mainly on the endurance of its main component, the power semiconductor. Therefore, particular attention is paid in this chapter to understand the models that allow the identification of features and early indicators of problems that establish the groundwork for early fault diagnosis in inverters. The two major switch technologies that control the market are field-effect transistors (FETs) and insulated gate bipolar transistors (IGBTs), which are bipolar devices integrating concepts from bipolar junction transistors (BJTs; IGBTs) which are bipolar devices integrating concepts from BJTs and FETs. From the beginning of power electronics, silicon-based semiconductors have been the undisputed king, but modern silicon-based power semiconductors are being challenged by silicon carbide (SiC) and more recently by gallium nitride (GaN). Regardless of the semiconductor material, early diagnostics in semiconductors are based not only on the understanding of the failure mechanisms but also on the “parasitic structures” that are intrinsically associated with the fabrication of the device. The identification and characterization of these “parasitic or associated structures” allow for the development of unified models with general characteristics across different materials and structures of power semiconductors. The aging effects are, in general, reflected in the parasitic structures early in the process of degradation, creating an ideal approach for understanding failure propagation. Fortunately, semiconductor devices share a similar structure, and a standard model across all power semiconductors is used in this chapter to understand aging and to enable early diagnostics.