We review the effects of microwave irradiation on low dimensional electron systems in Silicon nanostructures. Depending on the temperature and the energy scales involved, different effects may be observed on the transition probabilities of elastic and inelastic processes. In particular two cases of 0 dimensional confinement are analyzed, i.e., the trapping of a single electron in point defects close to a two dimensional electron system, and in single donor atoms trapped in the channel of a nanoMOSFET. Microwave dependent capture and emission phenomena and photon assisted tunneling are described in such kind of systems. Consequences on the single spin resonance detection and on the spin manipulation are discussed.