The course aims to illustrate the most advanced methods for the study, simulation and analysis of solid-state electronic and optoelectronic devices. The physical mechanisms underlying the operation of the most modern devices based on large gap semiconductors, such as GaN, GaAs and AlGaAs, as well as the more traditional ones manufactured in Silicon, will be illustrated. Moreover, through appropriate scale laws, the limits glimpsed for current technologies will be analyzed with the indication of possible solutions