Valuable information about defect profiles and defect concentrations in high-power semiconductor devices can be obtained by analyzing electrical device characteristics. This is demonstrated by evaluating reverse current-voltage characteristics of p-n junctions, from which the vertical radiation-induced defect profiles of the dominant generation center can be extracted. Measured data from proton-irradiated high-power diodes find a reasonable interpretation when radiation-induced doping effects, as obtained from spreading resistance measurements, are taken into account. Further investigations focus on defects in electron-irradiated power metal oxide semiconductor transistors, which were analyzed by stationary and dynamical diagnostic methods in combination with device simulations. Equipped with a detailed understanding of the action of radiation-induced defects, we make use of it in order to tailor certain characteristic electrical properties of high-voltage devices by exploiting carrier-trapping effects as well as radiation-induced changes in resistivity. The main focus lies on the blocking voltage and the switching behavior.