In-Operando local structural response of Si-based press-fit PN-junction diodes

• Semi-quantitative doping profiling revealed p-type, intrinsic, and n-type regions. • Doping effects predominate over thermal contributions in structural behaviour. • Asymmetric interfacial stresses, higher in heavily B-doped PN junction regions. • Heavily doped diode exhibited strongest structural response under current. Understanding the local structural evolution of silicon-based press-fit diodes under real operating conditions is critical for the development of reliable power electronic components. During operation, these diodes are exposed to high electric currents, leading to significant overheating and the generation of interfacial stresses caused by mismatches in the thermal expansion coefficients of the constituent materials in the device. These effects are further influenced by the doping profiles of the semiconductor junctions. In this study, we examine the structural response of single-crystal silicon in commercial press-fit power diodes both under room conditions (room temperature and no applied current) as well as under real current-driven operating conditions, focusing on localized regions defined by the doping profiles of three different PN-junction-based devices. The presence of dopants, along with the current-induced strain and thermal effects in the silicon lattice, leads to structural changes that directly impact device performance. By employing advanced in-operando characterization techniques, we resolve, for the first time, localized interfacial and region-dependent structural phenomena within operating press-fit diodes and establish direct correlations between lattice distortions, interfacial behavior, and doping concentration. These results provide new insights into the microscopic mechanisms governing reliability and degradation in high-power silicon devices under realistic working conditions.