Electron Holography allows both the amplitude and phase of a transmitted wavefront to be stored and subsequently recovered by a reconstruction of the hologram. Since both magnetic and electric fields change the phase of an electron wave that passes through them electron holography can therefore be used to directly, and quantitatively, image such fields. Significant experimental applications have already been made of this technique to the study of magnetic fields and materials, and electric fields have been studied in ferroelectric materials. Such a technique has particular value when applied to the study of semiconductor devices since these rely for their operation on the electric fields produced internally at P-N junctions or Shottky barriers. Holographic imaging of these fields will make it possible to accurately find the active regions of junctions as well as making it possible to measure the electrostatic fields that are present. Consider a cross-sectioned P-N junction of thickness t placed normal to the beam (figure 1).
Electron Holography Study of the Charging Effect in Microfibrils of Sciatic Nerve Tissues