A method for examining non-metallized semiconductor wafers without the use of any electrical or mechanical contact therewith is provided by the scanning of the wafer with an electron beam. The bombardment of the wafer with the electrons generates charges which are retained in the semiconductor material for a period of time depending on the structure and properties thereof. Defects in the structure, particularly in the structure of junctions, result in a diffusion of the charges with a consequent alteration in the energy of secondary emission which is also produced by the electron bombardment. The secondary emission is measured as the beam is scanned from point to point along the wafer to provide an image of the wafer. Differences in the intensity of points on the image show the desired junction characteristics and also indicate the locations of the defects in the wafer.