METHOD FOR OPTICALLY MEASURING ELECTRICAL POTENTIALS

The optical absorption edge of a semiconductor is shifted toward lower photon energies in an electrical field. The method of the invention utilizes this electro-absorptive effect in order to measure electrical signals of microelectronics in an optical way. A plate-shaped member arranged immediately above the component and scanned by a laser beam serves as a measuring sensor. This plate-shaped member is composed of a carrier crystal which is transparent for the radiation employed, of a conductive layer which is likewise transparent, and of a semiconductor which is dielectrically mirrored at the specimen side, the absorption behavior thereof being influenced by the electrical stray fields emanating from the interconnects. The measured quantity is the intensity of the laser radiation reflected at the dielectric mirror and deflected in the direction of a photodiode.