As device structures become increasingly complex, with the continuous emergence of novel materials, unconventional architectures, and new physical phenomena, the coupling of multiple physical domains, including thermal, electrical, and optical effects, is becoming ever more prevalent. At the same time, rising development and manufacturing costs place additional demands on modelers to deliver representations that are both accurate and computationally efficient across the entire chain from device physics to circuit behavior. Modeling serves two complementary purposes: theoretical models provide insight into the operating principles of devices, while also guiding design optimization and enabling engineers to fully exploit intertwined physical effects. Analytical modeling, however, often requires careful trade-offs among accuracy, generality, and simplicity. Models must be predictive enough to inform design while offering meaningful physical insight. In modern semiconductor devices, which often feature three-dimensional geometries, solving the coupled semiconductor physics equations analytically is extremely challenging or even impossible. Closed-form solutions are typically unattainable, so judicious simplifications are necessary to ensure that models remain tractable and practically useful. The papers in this Special Issue address these challenges by balancing physical fidelity with computational efficiency. They deepen our understanding of device physics while providing models that are both insightful and practical, with applications spanning cryogenic electronics, wide-bandgap devices, and radiation-hardened systems.
