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The outdiffusion process, which consists of the extraction of impurities from a semiconductor wafer by heating it to an elevated temperature in a high vacuum, is shown to be a practical method for the production of diodes and transistors. The usefulness of outdiffusion as a technique for device fabrication depends on how easily impurities can be evaporated from the crystal surface. The surface-evaporation velocity K which characterizes the ease of removal of impurities has been determined for the evaporation of antimony out of germanium at 700Â°C and is (1.5Â±0.5)Ã10-8 cm/sec. This value is large enough to indicate that it is definitely feasible to make high-frequency devices by outdiffusion. Narrow base germanium computer diodes have been fabricated that have a forward drop of 0.11 volt at 1 ma and that switch at speeds up to 5 mc. The operation of these graded base diodes is analyzed. Germanium n-p-n graded base transistors have also been fabricated which have grounded-emitter current gains, Ã, of over 100 and alpha frequency cutoffs, fÂ¿co, of above 200 mc.