A device for detecting electrical properties of a sample of an excitable material, in particular of a silicon wafer, comprises a microwave source for generating a microwave field, a resonance system which is coupled to the microwave source in a microwave-transmitting manner, the resonance system comprising a microwave resonator with at least one opening and a sample to be examined which is arranged next to the at least one opening, at least one excitation source which is arranged in the surroundings of the sample for controlled electrical excitation of the sample, and a measuring device for measuring at least one physical parameter of the resonance system.