The art of engineering

Photomicrograph of an internal view of crystal imperfections in a silicon diode. The photomicrograph was taken with a scanning electron microprobe at a magnification of 620. This new technique in microscopy developed at Bell Telephone Laboratories enables semiconductor diodes to be studied without damaging the specimens or using special treatment. The electron beam penetrates the material under study and a picture is produced by collecting the charges generated in the material by the beam. In this manner, opaque materialscan be examined. Beam energies from 4 to 50 keV are used with currents from 4 nanoamperes to 4 microamperes.