ABSTRACT
New observations of reverse-biased p-n junctions by means of transmission electron microscopy out-of-focus methods have been carried out, showing that a satisfactory agreement is obtained, provided charged layers are introduced at both of the specimen surfaces caused by electron irradiation. In order to circumvent the drawbacks and to obtain reliable results, researchers have tried to improve the specimen preparation techniques including the coating of a carbon layer on one exposed surface of the transmission electron microscope specimen in order to remove beam induced charging. In opinion it is however equally important to achieve a better understanding of tbe physics of the p-n junction when observed in the electron microscope, and for the task reverse-biasing is essential as it adds another degree of freedom under experimental control. Electron microscopy phase-contrast techniques, like holography or the more standard Lorentz microscopy methods, can be very helpful or even essential in the determination of two-dimensional dopant distributions on the nanometer scale.
