p−nJunction Transistors

The effects of diffusion of electrons through a thin $p$-type layer of germanium have been studied in specimens consisting of two $n$-type regions with the $p$-type region interposed. It is found that potentials applied to one $n$-type region are transmitted by diffusing electrons through the $p$-type layer although the latter is grounded through an ohmic contact. When one of the $p-n$ junctions is biased to saturation, power gain can be obtained through the device. Used as "$n-p-n$ transistors" these units will operate on currents as low as 10 microamperes and voltages as low as 0.1 volt, have power gains of 50 db, and noise figures of about 10 db at 1000 cps. Their current-voltage characteristics are in good agreement with the diffusion theory.